Stands for MimbleWimble Extension Blocks. Optional protocol level privacy that gives you very good privacy on chain. No addresses or amounts visible. It is also extremely scalable.

Slightly less private than Monero, because it doesn't obscure or hide input/outputs, but still a huge jump. Nice thing about MimbleWimble is that if you are not there to save the input/output data when it occurs, that information is lost forever.