Here’s a common error in the opening phase of the game, for beginners. The a-pawn or h-pawn should not be moved up two squares to develop a rook.
In the above position, white has just moved h4, a mistake. Some beginners make this kind of pawn move to bring out a rook early in the opening. Rooks are too valuable to be put into danger like that in the early opening. Save them for later.
This is probably something like what the beginner has in mind, but this is faulty. Black has easy ways of dealing with this opening idea. Look at black’s possible move d5. When the black pawn in front of the black queen moves two spaces forward, the bishop next to that queen now has an open diagonal leading to the square on which white’s rook was intended to move. If white then moves Rh3, black can capture that rook with that black bishop.
A rook is usually worth more than a bishop. In fact the ration is about five-to-three, so this method of opening development is a mistake. Even if the rook is not immediately lost, it can easily come under attack later in the opening or in the middle game.