They idea is that the page is generally about what gets mentioned the most. So if Google is looking at this we would want to see our target keywords variations mentioned more than any other topics. These variations are highlighted in yellow for you.
The goal isn't about getting the largest numbers. It is better to try and get more yellow than competitors and to try to get the yellow entries to the top.
Factors like the following are referring to the data in this report:
They are referring to how many of the top 3, top 5, top 10 are yellow.