What is https://screeps.com?
It's an open-source game for programmers, wherein the core mechanic is programming your units' AI. You control your colony by writing JavaScript.
Roles are a way to categorize tasks of creeps.
https://github.com/cbacon93/screeps/wiki/Roles
Operations to do to other rooms https://github.com/cbacon93/screeps/wiki/Operations
Controls reactions