The rook moves in straight lines: up, down, left, or right, as many squares as you like. It never moves diagonally, and it cannot jump over other pieces.
In these puzzles you slide the rook to the goal square past wall pawns. The trick is to think in rows and columns. Which row or column is the goal on, and how do you get onto it without a wall in the way?
Tip: a rook can reach any empty square on an open board in two moves. If a puzzle needs more, a wall is blocking one of those two lines, so go around it.