Tapping the "Rules" button on the bottom of the screen brings up this menu (below):
Selecting"General Rules" brings up this info screen:
Information is available for every piece type. In the example below, I've selected the help screen regarding the rook:
Below is the information for how the pawn moves:
Special moves are also covered in another "sub menu":
For example, if I select to read about castling, I get this screen:
There's more information on castling, so I can scroll down as needed to see the remaining information:
Similar informational screens exist for the other topics found on the Special menu. The initial option of the pawn moving two squares, pawn promotion, rules covering stalemate and draws, and the often mis-understood en-passent move all are documented well for those new to chess.