The knight moves in an L shape: two squares in one direction and then one square to the side. It is the only piece that can jump over other pieces, and every move takes it from a light square to a dark square or the other way round.
In these puzzles you hop the knight to the goal square. Wall pawns can't block a knight, but they do take away landing squares, so you still need to plan a route.
Tip: the knight can't reach the squares right next to it. If the goal is one step away, you'll need at least three moves, so plan a little loop.