关门 literally means 'to close the door' — 关 (guān) means 'to close' or 'to shut', and 门 (mén) means 'door'. As a verb, it describes the physical action of shutting a door, such as at home, in an office, or on a vehicle. It’s commonly used in everyday contexts like leaving a room, securing a space, or ending a visit.

In extended usage, 关门 also functions metaphorically to mean 'to shut down' or 'to cease operations', especially for businesses. For example, a shop that stops operating permanently is said to have 'closed its doors' — 关门. This figurative sense is widely understood and frequently appears in news reports and casual conversation about companies, restaurants, or institutions ending their activities.