This page lists the version history of a repository, as maintained by the git version control system. Each git version is marked with a commit id like 175ff44. (Note that these are shorthand ids, full git commit ids are even longer.)
If you click on a commit id (on the right) or on the commit message (on the left), you get the list of changes to files in the repository that have been introduced by this commit. If you click on the corresponding "Browse files" button, you will get a file browser for a past version of the repository, namely that specified by the commit. In order to remind you of the fact that not the latest version is being displayed, the commit will always be displayed in the file browser.