These play game shortcut toolbar icons give you quick access to common operations while playing a game against the computer:
Pause the game in progress. Stop the clocks (if present) so you can take a break. Click again to resume.
Force the computer to move immediately when the engine is thinking.
Take back your last move including the computer response.
Replay your last move. If you had previously performed a takeback, this icon will replay both your move and the computer response. If no takeback was performed this icon will replay the computer's last move played.
Change sides with the computer. You will be asked to confirm this, as you can imagine you should not do this in a rated game if you want an accurate chess rating.
Set up position enabling you to modify the current position and even set up a new one.
Toggle the coach on or off. The coach is on when this icon is highlighted. The coach provides move advice and warnings when you make mistakes or miss good moves.
Ask the computer for a hint move. This will be graphical demonstrated on the board.