For the source of Urban Dictionary, this a surprisingly well written para about taking a knee
An American football term for when the quarterback drops to one knee immediately after receiving the snap, thus automatically ending the play.
The use of taking a knee comes only near the end of a game when your team is in possession of the ball and holds a narrow lead (by a touchdown or less). If you execute a run or pass play, you risk turning the ball over and allowing the opposing team to gain possession and a chance to score. By taking a knee, you are able to run down the clock without putting the ball at risk.
A boring, if strategically important, play.
Further, it's used in some sports in practice to take a prayer or listen to a coach speak. It was then co-opted by Kaepernick in 2016.
I noticed last night that the Sky presenters were sans the BLM badges and instead had Kick it Out badges instead. I wonder how many corps will quietly roll back their support for the BLM campaign or rebrand it?