Return of Advertising Spend (ROAS) is a very important metric of success when it comes to any form of advertising. It is calculated by dividing the total revenue generated by your ads with the amount you spent on advertising.
Simply put, the campaign that I developed for an e-commerce brand generated a ROAS of 13, meaning for every $1 they spend on advertising, the return they receive is $13. So, if they spend $10, the return is $130 and so on.