To say ‘tell me’ in Spanish, you would say ‘dime’. This is the command form of the verb ‘decir’, which means ‘to tell’ or ‘to say’.
In Spanish, verbs are conjugated differently based on the subject pronoun and the tense. ‘Dime’ is an informal way of asking someone to tell you something, typically used with friends or people you know well. If you want to be more formal, you could say ‘dígame’. This is the formal command version and is appropriate when speaking to someone you don’t know well or in a respectful context.