As explained by Jordan Massey

To arms! Jordan Massey, gameplay programmer, explains the role of squads in Guild Wars 2's World vs World fights.

Short version; Squads are small groups of players with an undefined number, and a commander at the top. Each squad can chat, but only the commander (the squad creator) can speak to the masses. He can also define markers and objectives, with icons that represent orders like "defend" or "attack." But there's a catch - to be a commander you have to buy the manual. 

This level of organization counteracts much of the problem with giant PVP clusters yelling orders at each other, and putting the gold barrier in the way keeps rookie players from thinking they know better. All great changes to make WvW more streamlined.