The Edit Icon opens up all of the features that you can control for that frame. E.g. Background Colour, Image, Video, Overlay, Padding and Alignment etc.
The Plus Icon allows you to add a Content Component to this location of the page. E.g. Text, Image, Video etc.
HOLD THE ALT KEY and the Content Component component will be added to the top of the Frame.
DO NOT HOLD THE ALT KEY and the Content Component component will be added to the bottom of the Frame.
The Clone Icon duplicates the Frame and copies it directly below. This can be powerful if you are building masonry style blocks or if you would like to repeat your content in lists.
The Delete Icon deletes the Frame and the Components within it.
ADD NEW FRAME TO THE OUTSIDE:
It is possible to add new Frames to the outside of any Frame. This has many uses for advanced users, such as being able to any many layers of graphics on top of each other and controlling their background position and behaviour.
You can remove any Frame, unlike 'Delete' this removes the Frame but does not delete the components within it.