How does it work and what do you need to do? Are you receiving points just for using bing and google?
See here for more information:
https://www.microsoft.com/en-us/rewardshttps://support.microsoft.com/en-gb/hub/4294457/microsoft-account-help#rewardsEssentially, there are a bunch of things you can do to earn Microsoft Reward points, including use Microsoft Edge, use Cortana, search on Bing via desktop and mobile, Xbox One games and quests, and additional daily tasks such as quizzes and surveys. There are a bunch of different rewards you can redeem them for, including Amazon gift cards, in the general ballpark of 5000 points for $5 of reward.
It's not exactly efficient, but if it's things you are doing any way, then you might as well cash in. The massive downside is obviously that you have to use a bunch of Microsoft products, which is terrible for privacy, and they are probably making more profit from selling your data than the cards are worth.