Numbers if cell is equal to X or Y
This is thankfully quite easy. You can achieve what you want using the OR function in Numbers (this function is also found on Microsoft Excel):

IF(OR(A1 = "Apple", A1 = "Orange"), "Fruit", "Not a fruit")


The argument for the IF function here is OR(A1 = "Apple", A1 = "Orange"). This OR function tests whether any of the arguments are correct; if they are, it returns TRUE. If none of them are correct, it returns FALSE.