Bio break refers to a general break for one's body: stretching one's legs, going to the bathroom, getting a drink of water, etc. The term is generally used during meetings, presentations, and other workplace occasions.

Bio break（字面意思为“生理休息”）指让身体稍事放松的小憩时间，大家可以伸伸腿，去下卫生间，打杯水等等，这里译为“会间小憩”。这个词多用在会议、演示讲座等职场活动中。

For example:

Let's take a 10 minute bio break and be back in our seats at 3:30.

我们会间休息十分钟，请在3点30分回到座位。