What's going on here
This is a new way to donate to Phuks without needing cash, paypal, or a credit card.
Your computer is basically being given a math problem to figure out, and part of the problem includes a random number. Every time it runs, you get a different result. Your results, along with billions of other results from other users are grouped together and submitted to a service that pays us for them. They pay us using a cryptocoin, Monero (XMR), which we can use to pay for domains, hosting, and other costs associated with keeping the site up and running.
How it affects you
If your computer has 4 cores and you set the thread count setting to 2, you are basically donating half of your computer's processing power. While mining, your computer will draw more power and run hotter. Depending on your machine, if you run it full time, you may see 50-100 watts of extra power draw resulting in your power bill going up a few dollars a month. Your computer can only do so much at once, so if you experience slowdowns while trying to do other stuff, you can adjust the thread count or throttle to free up some resources. This isn't recommended for small laptops or mobile devices. Most batteries are not made to keep up a higher power draw for long periods of time.