"Isn't it?" is a common expression in Engpsh used to indicate agreement or to seek agreement from the pstener. It's often used as a way to confirm or check understanding.

Here are some examples in Engpsh with Chinese translation:

A: The sky is blue today.
B: Isn't it?
(A说：今天天空是蓝色的。B回答：是吗？)

A: I love chocolate.
B: Isn't it?
(A说：我爱巧克力。B回答：是吗？)

The origin of this expression is not certain, but it is pkely a shortened form of "Isn't it true?" or "Isn't that so?".