Okay, so O Antiphons are like seven special songs we sing in church during the week before Christmas. Each song talks about something special or awesome about Jesus, and uses a special title to talk about him.
The first song talks about how Jesus is like a wise king who brings hope to everyone. We call him "O Wisdom."
The second song talks about how Jesus is like a leader who guides us and helps us know what to do. We call him "O Lord."
The third song talks about how Jesus is like a strong and powerful ruler who makes everything right in the world. We call him "O Root of Jesse."
The fourth song talks about how Jesus is like a brilliant light that shines in the night and helps us see. We call him "O Radiant Dawn."
The fifth song talks about how Jesus is like a faithful friend who saves us and helps us. We call him "O King of the Nations."
The sixth song talks about how Jesus is like a great teacher who shows us what God is like. We call him "O Emmanuel."
And the seventh song brings all the other songs together and says how awesome Jesus is and how much we love him. We call him "O Come, O Come, Emmanuel."
So basically, O Antiphons are seven special songs we sing in church to talk about how awesome and special Jesus is, and how much we love him.