Function pointers that call one function
bb_perip is a function that returns a pointer to a bit from a register that is related to a specific timer peripheral (there's more than one).  That pointer is then dereferenced with the * operator to make *bb_perip(...). 

What bb_perip returns is dependent on what timer you are using and what value you are interested in.

bb_perip is not a pointer to a function, it is a normal function that happens to return a pointer.