Why my grand baby is jumping in his sleep since he had his 1 year old shots?

Hard to tell... "jumping in his sleep" usually means a child moves around a lot in his sleep. That happens in many kids, but can happen more often if he had a rough day (got poked a few times). "since he had his 1 year old shots" doesn't say how long after the shots (1 day, 1 month, 1 year, etc.), so it is hard to tell if anything is related to getting poked. If related, maybe the legs are sore or he is dreaming.