Both translations are correct but depend on the English variant you're using. For international communication, consider your audience - use soccer for American contexts and football for British contexts. The key is matching the terminology to regional conventions.
他是第十中学的足球运动员用英语怎么说
He is a soccer player at No.10 Middle School. In American English, we usually say soccer to refer to the sport played with a round ball, as opposed to American football. This translation works best in contexts where American English is commonly used.
In British English, the same sentence would be 'He is a football player at No.10 Middle School.' The term football in UK English specifically means what Americans call soccer, while 'soccer' is rarely used in everyday conversation there.