Guilds are here
https://forums.galaxy-of-heroes.starwars.ea.com/categories/player-guilds
In game there isn't any guild feature yet, you can apply to my guild if you are from Oceania :)
The advantages right now are high level allies (if you're low level), stratergy talk, getting to know people and just having fun.
Right now they are just a foundation to create a 'real guild' when they are available in game.