A playhouse has two common meanings. It can be a small building or structure, often in a garden, sized for children to play in like a tiny house of their own. It's also an older or more formal word for a theater, a building where plays are performed, and you'll still see it in the actual names of some real theaters, like "The Liverpool Playhouse."

兒童遊戲小屋;劇院(較舊式的用法)