@FunkOff It's for tournaments. Many tournaments have a system of establishing one or more map pools for the tournament (e.g., different map pools for Groups A B C and D during LotS, and another map pool for the Round of 8). With this system, often players are allowed to ban (veto) a certain number of maps and then the players choose from what is left for the tournament games.
The process of map selection requires players to understand the process or else it creates extra work for TDs. This is a software tool for automating the process of map vetoes/map selection, to make it easier for everyone involved.