Vitess is an additional layer on top of MySQL which all queries pass though. Among other things, it implements its own query parser which can then do stuff like split a query across shards and join results etc.

I wouldn't say there's too much "magic" in there, but it does a lot of known difficult things (schema management, sharding/resharding, connection pooling, query optimization, DB administration, monitoring, backup/failover) which are generally painful and expensive to do yourself.