Au fond is a fancy way of saying "basically" or "fundamentally." We are, au fond, just trying to help you learn fun and useful new words and phrases.
Au fond comes from a French expression literally meaning "at the bottom." In English, though, we almost always use the phrase figuratively to describe the true, underlying nature of a person or situation. It's similar to English expressions like in essence or deep down or at heart. For example, one might say something like "He acts like a cynic, but au fond, he's a hopeless romantic."