It's hard to pin down exactly what Multiversity is at this point in the overarching sense. 7 of the issues take place on different worlds and seem to have somewhat self-contained stories, but the overall story set-up in the first issue is that a group of powerful, evil beings are going about the multiverse, and basically mutilating and corrupting different Earths, and a group of superheroes from the multiverse has been called together to the old Monitors station to combat them. That bit was set-up in the first issue, and will be resolved with the final issue. The issues in-between will be set on different Earths, and as of issue 2, it's not super clear how exactly the narratives will bled into each other.