You are right. It has a different meaning here.
"Il y a pas mal de cafés." means 'There are quite a lot of cafes'.
Another example would be 'J'ai pas mal de travail', meaning 'I've got quite a lot of work' or, perhaps, more idiomatically 'I've got a fair bit of work'. 'Pas mal de choses' means 'quite a lot of things', and so on.