When you stow something, you store it or pack it away neatly. If you move into a tiny college dorm room, you might have to stow your shoes under the bed.
On an airplane, you are only allowed to bring small suitcases that you can stow in the overhead bins or under the seat in front of you. In an adventure novel, pirates might stow their treasure in a seaside cave. In Old English, stow was a noun, meaning "a place or spot."