It would be like a program where you give it a number of factors, and when those factors coincide, the algorithm will alert you. A good example of how this is used for abuse-fighting purposes, if you look at sexual exploitation, you could say to the algorithm to flag any account that is contacting somebody who has provided their age to us and is a minor and is using certain keywords within a specific time frame. If you have a lot of these patterns of behaviour happening at the same time, it will let us know.
The algorithms are a very smart way to let the system alert you to specific situations that might be happening that you might not know unless somebody has reported it to you.