Help with a if formula

I am trying to set a value based off if it its equal to a bank of words. How to i make a if statement so that the if for example x= something from a word bank then it equals the corresponding y from a word bank? Im trying to get a if statement so that if the value in C column on the left equals the C column on the right then the B column equals the corresponding B value that the C column is equal to on the right other wise leave blank.