The program’s editing windows are available from both the Editor and the Browser. Unlike the Editor, the Browser enables batch editing—editing of multiple photos at once. If you select multiple files and visit an editing window in the Browser, you are making a batch edit.
If not even one file is selected, then you cannot perform direct operations (rotation and flipping), but the ones that lead to an editing window are still available—in this case, they apply to every file in the current folder.
Edits you make in the Browser are always irreversible: the change is saved to file immediately!
So here as always: edit copies of your pictures, not the originals.
Picture Editing Functions