I'm an English learner and I read this news below:
Concussion? Oh, got a little ding on the head, no, no you can't play for the rest of the season. Our people are tough! Trump said.
What's the meaning of "ding on the head"?
The way I see it, ding is synonymous with injury, possibly bruise, in this case. It's just an extension of the following:
ding noun [ C ] (DAMAGE)
US a small damaged area on a surface where something has hit it:
She had the ding in the paintwork repaired.
In my opinion, it's a colloquial usage. On the head is literal. In other words, Trump is literally saying the person has a small injury on their head. This is an inaccurate description as the injury (concussion) does not occur on the surface of the head, but rather within the head. Also note that he's minimizing the severity of the injury.