The 'Practice History' window shows all the practice sessions of the current piece by the current user, listed from the most recent. It also shows your best performance, and when you last played the piece. You can reorder the columns using the header of each column.
History items show you information about an individual practice session. Items with a green/yellow play icon next to them have the recording of this practice available to listen to. A green icon means that the practice recording is saved in the library permanently, whereas a yellow icon means that the recording is saved in the library temporarily. A grayed icon means that the recording is no longer available. Double click on an item to see its Performance Report. Right click on an item to see further options.