Sort of. MLS is not really meant to replace Signal but it's definitely a significant improvement over Signal for certain things.

Signal and MLS both use a double ratchet system of encryption that gives you both post compromise security (e.g. you can recover from a breach in the normal course of using the protocol) and forward secrecy (e.g. someone getting a key now can't decrypt everything going back in time).

MLS and Signal are effectively the same when it comes to 1:1 messaging. Where MLS is significantly better is in private group messaging. It's far more efficient and comes with strong security guarantees to the group's current state (e.g. you have cryptographic certainty of the list of members in a group at all times).