The tool bar provides shortcuts via buttons to some typical actions: creating a new file, opening a file, saving the current file; undo/redo last editing; go to previous/next location; select build mode, compile file, build project, clean project; start/continue the debugging session, step/next execution, finish current procedure.
The icon on the far right of the tool bar will be animated to indicate that an action (e.g. a build or a search) is going on in the background.