Procedure can only perform some action:
procedure Display(x, y: integer);
begin
WriteLn(IntToStr(x * y));
end;
// ...
Display(3, 4);
//...
Function is a procedure which may also return a result:
function Multiply(x, y: integer): integer;
begin
Result := x * y;
end;
// ...
WriteLn(IntToStr(Multiply(3, 4)));
// ...
Don't ask such basic questions btw, you can find such stuff in every available pascal/delphi tutorial.