Question

what is the use of flip tools

Answer 1

The Flip tool provides the ability to flip layers or selections either horizontally or vertically. When a selection is flipped, a new layer with a Floating Selection is created. You can use this tool to create reflections.

Answer 2

To do this, you can just hold  down the Ctrl and Alt keys and any arrow key to flip the screen 90 degrees, 180 degrees, or 270 degrees. The display will go black for a second before it displays in its new rotation. To get back to a normal  rotation, simple press Ctrl+Alt+Up arrow.