TypeOf

TypeOf[expr] gives the type of expr without evaluating it.

TypeOf[expr,Typed[x,ty]] assumes that instances of x in expr have type ty.

TypeOf[expr,{Typed[x1,ty1],Typed[x2,ty2],…}] assumes that xi has type tyi.

TypeOf[expr,decls] uses declarations decls.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.