What does el hermano de mi padre es mi mean?

'My uncle's brother is my....'

This looks like a fill-in-the-blank question for a Spanish class, where you're expected to be able to understand the sentence and complete it. However, if this is a fill-in-the-blank question, it's a singularly bad one. The answer could be "father." It could also be "other uncle", or even "no official relation" (if the uncle in question is your uncle only because he's married to your aunt, instead of being a blood relative of your father or mother).