房门 (fángmén) means "room door" or "the door to a room." It specifically refers to the door of an interior room, as opposed to a main entrance or gate.
请随手关好房门,谢谢。
qǐng suíshǒu guān hǎo fángmén, xièxie.
Please close the door behind you, thank you.
他轻轻推开房门,发现屋里亮着灯。
tā qīngqīng tuī kāi fángmén, fāxiàn wū lǐ liàng zhe dēng.
He gently pushed open the door and found the light was on inside.
风太大了,房门被吹得砰砰响。
fēng tài dà le, fángmén bèi chuī de pēngpēng xiǎng.
The wind was so strong that the door was banging loudly.