There are a couple words for "uncle" in Mandarin Chinese, as seniority and the place you are in on a family tree deeply matters for Chinese speakers.
For father's older brothers, we call them 伯伯(bóbo.)
For father's younger brothers, we call them 叔叔(shūshu.)
For mother's older and younger brothers, we call them 舅舅(jiùjiu.)
叔叔(shūshu) is also used to address men who are about your father's age but younger, while 伯伯(bóbo) is also used to address men who are about your father's age but older, even when they are not related to you. You might see Chinese speaking parents urging their children to address people with appropriate terms like these to show respect.