Number + 楼
二楼 (èr lóu) is a noun meaning "second floor." In Chinese, floor numbers are formed by combining a number with 楼 (lóu, "floor/story"), making this pattern productive for referring to any floor of a building.
我家住在二楼,出门很方便。
Wǒ jiā zhù zài èr lóu, chūmén hěn fāngbiàn.
My home is on the second floor, so it's very convenient to go out.
请到二楼的会议室开会。
Qǐng dào èr lóu de huìyìshì kāihuì.
Please go to the meeting room on the second floor for the meeting.
二楼新开了一家咖啡店,你去过吗?
Èr lóu xīn kāi le yī jiā kāfēi diàn, nǐ qù guò ma?
A new coffee shop opened on the second floor — have you been there?