This is why I don't like all those placeholders.
Hop means just hop forward. Haku's dash. You do Gurren and then hop forward and start an aerial combo that has Haku ascend like he's going up a stepladder.
I'm not sure which juggle that's referring to, but the classic always was:
3C > 2B > Gurren > hop 5A > j.A > j.B, j.2A > j.C.
You do j.A and j.B in your first jump, and j.2A > j.C in the second jump.