The noun 椅子 (yǐzi) means "chair" and refers to a common piece of furniture for sitting. It often appears with location words such as 上 (on) to indicate being seated on it.
教室里每个学生都有一把椅子。
jiàoshì lǐ měi gè xuéshēng dōu yǒu yì bǎ yǐzi.
Every student in the classroom has a chair.
这把椅子坐着很舒服。
zhè bǎ yǐzi zuòzhe hěn shūfu.
This chair is very comfortable to sit in.
他搬了一把椅子到阳台上。
tā bān le yì bǎ yǐzi dào yángtái shàng.
He moved a chair to the balcony.