Plural of 'kimi' (you); used to address a group of familiar or lower-status people. Casual, masculine in tone, and can sound brusque depending on context.
君ら、今日の宿題はもうやったのか？
You guys, have you already done today's homework?
君らのおかげで試合に勝てたよ。ありがとう。
Thanks to you guys we were able to win the game. Thank you.
先生が黒板を指して、君ら、よく見ておきなさいと言った。
The teacher pointed at the blackboard and said, 'You lot, watch carefully.'