KudoCoins are a way to say "Congrats!", "Well done!" to your friends on Strava. A bit like Strava Kudos. Except... You have a limited amount of them. You get KudoCoins either by providing a "proof of work" (i.e. your completed Strava activity), or by receiving some from your friends. Either way, to get some, you need to get moving!
This extension makes it easy to send coins to your friends by inserting a convenient kudocoin button on Strava, right next to the usual "Give Kudos" button. Clicking it pre-fills a "Send Kudocoin" form with the activity author and activity link, so you don't have to fill those by hand, and it will also avoid errors filling them.