President Joe Biden and his wife Jill were taking calls when one guy called up, wished them a Merry Christmas, then said 'let's go Brandon.'

Joe Biden responds with "let's go Brandon, I agree" and continued the call, but the video seems to be cut off at that point.

I am somewhat curious of one thing - does Joe Biden know what 'let's go Brandon' actually means? Does he??? Or does he think the caller was just saying something random and he was agreeing with it to make the caller happy?