A wooden crate is used as a means of item storage, with a capacity of 50 weight. They can be stacked up to three high, giving 150 capacity, the second highest storage for a single tile (second to the metal crate).
A wooden crate, like any other container, can be destroyed by a sledgehammer. If it is destroyed, all of its contents will spill onto the floor. Furthermore, any crates stacked on top of that crate will fall down.