"As well" is interchangeable with "too" or "also". E.g. I'm sad, but I'm angry too = I'm sad, but I'm angry as well. Can you also give me a size 10? = Can you give me a size 10 as well? (It's more normal to say as well at the end of the sentence) "As well as" is interchangeable with "and", "plus" or "in addition to". E.g. I'd like the soup and the wings = I'd like the soup as well as the wings. He plays the guitar and the drums = He plays the guitar as well as the drums. You could say, "He plays the guitar, and the drums as well."