It depends on which version of Fortran you're thinking of.
Fortran IV and Fortran 77, probably BASIC in terms of facilities. They also have Fortran specific goodies like arithmetic ifs, common blocks (Coral66), formats (C), multiple precision arithmetic (C), namelists that you may not find in the language you are using.
Fortran 90, 95, 2003 possibly Pascal or C in terms of facilities. They also have Fortran specific goodies which you won't find anywhere else like array processing.
Easiest way to learn is to pick a problem and try programming it. There are quite a few free compilers about.