Yes RE always generates a language, infact it is one of the way of describing regular languages apart from Finite state machines and regular grammars. Some of the languages generated by primitive RE are PHI, NULL STRING i.e. {€} & {a}. Other languages are derived from these primitive REs by a finite number of applications of R1+R2 (Union), r1.r2 (concatenation) , R1*(closure) & (R1).