From the Super Mario Wiki
Wario with some Arrow Blocks surrounding him.
Arrow Blocks are gray, metal blocks found inside Wooden Trapdoor sublevels in the game Wario World. The Arrow Block looks like a gray block with four red arrows pointing in the four cardinal directions on each side. If Wario punches the block, it will go sailing in a straight line until it hits a wall causing it to stop; if it hits another Arrow Block, that block starts to move instead, potentially resulting in a chain reaction of multiple blocks. Arrow Blocks are generally used as platforms to help Wario reach previously inaccessible ledges containing Red Diamonds and Golden Statue Parts.
Blocks with arrows also appeared in Super Mario Bros. 3 under the name Arrow Lifts. A platform that moved in the indicated direction would emerge from the block when landed upon.