WESA stands for World E-Sports Association. The association is designed to defend the rights and needs of gamers as well as implement the unified standards of leagues, tournaments, and championships. WESA has been founded by ESL together with major gaming powerhouses, such as Fnatic, EnvyUS, NiP, G2 Esports, Virtus Pro, Na'Vi, and MouseSports.
WESA's mission, according to the official website, is following:
"WESA’s mission is to become the global benchmark for industry-wide standards through that framework, involved parties and activities of the Association. Starting with the ESL Pro League for Counter-Strike: Global Offensive, WESA will be the first organization in the history of esports that will bring those affected by its decision most, to the decision making table. Transparency towards Teams and Players, as well as a continuous support to them are at the heart of the Association."
As of now, WESA only covers the Counter-Strike part of E-Sports, but it is obvious that this only the beginning and organization will expand onto other major E-Sport titles.