"good second kids bike"
That's not what it says!
Try this:
The seller has ONE child, who happens to be a boy (ie: His son).
The son had a first bike, which we'll assume was a YZ80.
Then he got his second bike, which was this KX125.
Now the kid wants something better, so the KX is for sale.
"second bike for our son"
Now I understand why Mainline lives in Queensland. Once I work out why Vandy and Barsby are there, we can start building a wall around the place.