Going by the examples you've provide:
13pb15 - no idea. I don't know what pb is supposed to represent. It's worth noting, though, that some tabbers will occasionally use their own notations instead of the universal givens. I'd have to see the tab itself, maybe then I could figure it out from context.
5h6h7 - “h” stands for “hammer on.” You start with your index on the 5th fret, hammer your middle finger onto the 6th fret, then hammer your ring finger onto the 7th fret. You're using the sudden pressure of the applied finger to ring the note rather than picking it.
3s - no idea. I'd need to see the tab for context.
7————–7——- - also not sure. Again, I'd need to see the tab.
3b - typically in printed notations, b means bend.
5/7 - / usually means slide up. So you'd slide up from the 5th fret to the 7th
And welcome to bass guitar. Here's to hoping you enjoy it as much as we do!
