It means to summarize. To present the substance of (material) in a condensed form; summarize: sum up the day's news; concluded the lecture by summing up.

Sum in English is to add as in mathematics. So, to say that "sums up" Andy for me says that tells Andy's story. Or simply to say that is what Andy is about his personality, whether or not he is nice, honest. Just about everything about Andy. .

thanks

You can sum something or someone up in a short sentence, saying the main things about that person or thing. For example: "She is very rich, she wears a crown and has a huge family. That just about sums up the Queen" It's a sentence tag that you add on to the end of a short description of someone or something to express that there's not much more you can say to say it better.