Your question appears incomplete, however, what is written translates to: 3(4+x).
A product is multiplication - so the product of 3 and (whatever follows) means that you are multiplying 3 and the number or expression that follows the "and". In this case, what follows is "the sum of 4 and a number". A sum is addition, so we are adding 4 and "a number" which we will call x: 4 + x. Since the sum is an expression, the three must multiply the entire expression, because it multiplies with what ever follows the "and" in the statement.
Final answer: 3(4 + x)