How to execute function in SQL Server [closed]

I built a function and I am trying to execute it… but some errors are occurring

CREATE FUNCTION dbo.Afisho_rankimin
(
    @emri_rest int
)
RETURNS int
AS
BEGIN
    Declare @rankimi int

    Select @rankimi = dbo.RESTORANTET.Rankimi
    From RESTORANTET
    Where dbo.RESTORANTET.ID_Rest = @emri_rest

    RETURN @rankimi
END
GO

SELECT dbo.Afisho_rankimin(5) AS Rankimi
GO