Most likely, you'll get a bunch of smaller garlic bulbs or rounds (single garlic cloves instead of a differentiated bulb) growing in clumps - 1 clump for each head of garlic that grew last year.

They're definitely still good to eat. If you want to experiment a bit on a few of the clumps, wait until you can dig into the soil and separate the individual plants out leaving just a single plant growing. Try not to disturb the roots too much but that'll be tough. By giving 1 plant the proper room, you might get the large bulb that's normally grown and you can use the thinnings like garlic scallions.

Firstly, don't worry. Garlic is very robust.

In some ways, you are better off if you get rounds as they will yield much larger bulbs if you re-plant them. In general, save the largest cloves to re-plant in the fall, and eat the rest. Yum.