When you talk about the twenties, you are referring to numbers between 20 and 29. For example, if you are in your twenties, you are aged between 20 and 29. If the temperature is in the twenties, the temperature is between 20 and 29 degrees.
双语例句
例： They're both in their twenties and both married with children of their own.
他们俩都二十几岁了，都已结婚生子。