Try this example will test if A1=1 And B1=2 Then Sum A1 + B1 =3
=IF(AND(A1=1,B1=2),A1+B1,"False")

XL interprets any non-zero numeric value as TRUE and zero as FALSE, so,
literally:

   =IF(AND(A1<>0,B1<>0),A1+B1,"Something else")

OTOH, XL coerces TRUE to 1 in math formulae and FALSE to 0, so "if A1 is
true then B1 is also true" translates to

B1:     =IF(A1=TRUE, TRUE, "Something Else")

and

result  = IF(A1=TRUE, A1+B1,"Something Else Again")

which will always return 2 (TRUE+TRUE===> 1+1).