Show only modified files in a Github Branch

Why Unmodified files are displaying in Branch
See below picture for understanding,

Is possible to display only modified files when selecting lesson-02 branch

That’s as it should be: The file browser shows the state of the current branch, not changes relative to anything.

If you’d like to see the changes you should look at the commit(s), or check the “compare” button (in your second screenshot directly below the green “code” button).