Use 一下 (yīxià) to express a brief action in Chinese grammar. Often, adding 一下 just makes the Chinese feel more natural. This is not something you can get a feel for quickly. You'll want to observe how native speakers use 一下 over a long period of time to really get used to how it is used.

Structure
To express that a verb is carried out briefly or "a little bit," you can add 一下 after it.
The structure is:

Examples

Nǐ kàn yí xià.
你 看 一下。
Take a quick look.