It returns %client.slyrTeam (which is a scriptgroup) after it does some checks.
Edit: Here is the %client.getTeam function, so you can see:
function GameConnection::getTeam(%this)
{
%mini = getMinigameFromObject(%this);
if(!isSlayerMinigame(%mini))
return -1;
if(!%mini.Gamemode.teams)
return -1;
if(!isObject(%this.slyrTeam))
return -1;
return %this.slyrTeam;
}