预热的意思是提前把东西加热好，做菜以前经常要给烤箱预热。

The meaning of 预热 is to heat something in advance; for example, you often need to preheat the oven before cooking.

这个词也可以说做事情以前的准备，比如比赛前先做一些预热运动。

This word can also mean preparation before doing something, like doing some warm-up exercises before a competition.