This is Goten, looking extremely happy with himself as he first learns to fly. Goten is my favorite character from DBZ and this is one of my absolute favorite moments from the series. I was VERY excited to spot this sketch on YJ and recognized it immediately ^_^ He's just so adorable in this shot XD

According to the seller, it is a layout correction sketch. From the note, it seems the animator wasn't satisfied with the ending/settlement portion of the animation, so they drew this correction. It mentions letting Goten say his lines like this, I guess meaning let him speak while he's in that position? Makes sense.

This is from episode 192, Videl Takes Flight (or 207 if you go by the uncut Japanese version)

Screencap from HDDBZ's youtube upload (Thanks :D).