It appears to be a 6 or7-spd HyperGlide freehub. The lockring is missing or ripped off. Here's a guide on how to remove the cogs & freehub body: Park Tool: Freehub service. Just use the Shimano section.

The pawls on the centre looks in good shape actually, not too rounded off at the tips, not too worn. Most likely all you had to do was disassemble the parts in the correct order with the proper tools and all you'd need was some new grease in the freehub body to get things running smoothly again. As it is, you'll need a new freehub body now along with a new cogset.