brush up on

Meaning

To improve a skill or knowledge that you already have but have not used for some time.

Examples

1. I need to brush up on my French before the trip to Paris. US UK
2. She is brushing up on her maths for the exam. US UK
3. Brush up on the company’s products before the interview. US UK

How to use it

It has three parts: brush up on + the skill or subject. It suggests that you knew the skill earlier. For something completely new, use learn or study.

Common mistake

Not: I will brush up on a new language this year.
Say: I will learn a new language this year. (Brush up on is only for something you already know.)