sounds like it turns your computer into a tor exit node?
Not at all. Snowflake belongs to the family of pluggable transports, and offers a connection to an entry node in the Tor Network. Just like a traditional bridge, with the advantage that the higher number of individual, constantly moving IP's makes blocking them by oppressive regimes more difficult.
It uses WebRTC to disguise the traffic as a real time peer to peer communication, like video/voice call.