When you open the project, Android Studio notices some unversioned item in your project’s working copy and prompts you to ask whether this item has to be added under version-control or not. In terms of svn.exe command-line client, Android Studio asks you to
svn add the item.
svn add command schedules files, directories, or symbolic links in your working copy for addition to the repository. The next time you will
svn commit new revision, the addition will be committed to the repository.