Question on Scrum Definition

The paragraph above that should help: 

Scrum is simple. Try it as is and determine if its philosophy, theory, and structure help to achieve goals and create value. The Scrum framework is purposefully incomplete, only defining the parts required to implement Scrum theory. Scrum is built upon by the collective intelligence of the people using it. Rather than provide people with detailed instructions, the rules of Scrum guide their relationships and interactions.

My thoughts about the paragraph you mentioned: 

Scrum requires that the cross-functional team have enough experience and knowledge in the work they will be doing in order for them to decide which processes, techniques and methods they should decide to employ in order to accomplish that work. 

The Scrum team utilises the three pillars of empiricism, along with them living the five scrum values to help them make their decisions. 

can anyone please elaborate the above statement marked in bold with some example and reference , that will really help me understand the definition thoroughly.

My advice is not to look for elaboration, but for simplicity. Scrum begins with Done. 

So whatever the "processes, techniques and methods" being used actually are -- things which will vary by context -- Scrum will assure a finished and usable increment every Sprint.

If the organization must change for this to happen, we can expect Scrum to highlight the matter very quickly.

My advice is not to look for elaboration, but for simplicity. Scrum begins with Done. 

Very good advice.  I will add that in my experience some organizations/teams have focused entirely on Done and neglected the other important piece...Value.  I would augment @Ian Mitchell's statement to "Scrum begins with something valuable being Done." 

@Scott Anthony Keatinge provides a very valuable lesson.  Just as the Scrum Guide does not provide you all the details, it also is very purposely written.  You shouldn't focus on a single paragraph or sentence.  Focus on the concepts and value that is provided by the entirety of the text.  Just as a trail guide will lead you along a path to a specific place and point out various items of interest, the Scrum Guide will guide you to a valuable way of doing work that will benefit internal and external people. 

As I generally agree with above comments, IMHO we should not omit value of diving a little deeper with study effort. Overthinking and oversimplifying things can be equally harmful to our understanding. Trying both approaches and balancing them may be best to form proper understanding.

Let’s dive a little with that paragraph in question and elaborate on it:

Various processes, techniques and methods can be employed within the framework. (…)

After couple of readings of the Scrum Guide it should be rather clear that on its own Scrum does not offer / prescribe too much of techniques on its own. Think for example about Refinement, this concept is generally described as “(…) the act of breaking down and further defining Product Backlog items into smaller more precise items. This is an ongoing activity to add details, such as a description, order, and size. Attributes often vary with the domain of work.“ However, how you perform it is up to you. So you may for example already had in use such techniques as User Story and User Story Mapping, Gherkin, Epics, 3Amigos, etc. Whatever it is, there is nothing in Scrum that will prevents you from using it further, or from employing other techniques.

With that in mind, we can swiftly move to next sentence:

(…) Scrum wraps around existing practices or renders them unnecessary. (…)

As I mentioned before, there is nothing in Scrum that prevents you from using existing elements. However, when we think about what Ian and Daniel said, Scrum approach will boils everything that you do into one simple question - Do you have Done useful Increment of value at the end of the Sprint? Regardless of the answer, yes or no, you may either seek how to unlock your possibility to create Done Increment, or how to do it even better - in other words, we seek effectiveness in our work. Therefore, some practices may be rendered unnecessary when you start using Scrum. For example, phases approach with detailed analysis may be something rendered unnecessary, or status updates / forms may be rendered as such. Both may be not longer relevant due to i.e effectively performed Scrum Events.

(…) Scrum makes visible the relative efficacy of current management, environment, and work techniques, so that improvements can be made.

Here it might be tricky to grasp meaning as efficacy is not commonly used word, and as far as I know, it have not good translation into my native language. However, as far as I understand, we could think about it as “how we think about ourselves effectiveness”. For example, I may say that I am able to improve your service quality by factor of two, and that will display my self-efficacy. However, when we use Scrum, that is build on empiricism, by design we should compare that to real world experience, to what we observe in our context, or within our competition. That will makes visible the relative efficacy. So for example, I may improve that quality 2x, however compared to what we observe we may still be far from what is possible. Or, I thought that I am able to do that, but in reality I only managed to get 1.2x better. Whatever is true, regardless of our goal, efficacy of our management, environment and work techniques will have significant impact on our ability to achieve it.

Summing things up and paraphrasing this definition a little:

You may use within Scrum whatever techniques and practices you may wish. Thanks to Scrum’s empirical, iterative and incremental nature, it will quickly gives you feedback if those are helpful things or not. As you use Scrum, due to that nature, it will highlight also big picture - your management, environment, and work techniques. And help you introduce improvements so that they will rather help with producing anticipated outcomes, rather than hinders those efforts.