Hi there!
Distributive property are two big words that basically just mean you need to distribute the 3 to the whole parentheses. This means you need to multiply 5 by 3 and also 6 by 3.
3 × 5 = 15
3 × 6 = 18
Now that you've distributed the 3 to the entire parentheses, you just need to add together both answers you got :
15 + 18 = 33
Your answer is: 33
There you go! I really hope this helped, if there's anything just let me know! :)