He looks good. You can watch videos online to learn how to sex him/her yourself. but unless you plan to breed him/her I wouldn't even bother. I would say that he is between 2 and 5 months old. Make sure you weigh him so you know how much to feed him. a ball python should be fed 10%-15% of his/her body weight once or twice a week. (I feed mine twice a week until they are 450 grams then only once a week).
Just going to go over the basics just in case. (Sorry if this is redundant)
Make sure he has 1/2 of the cage between 88 and 92 degrees F, and the other half is between 78 and 82 degrees F. Keep the relative humidity between 40% and 60% except when he goes into shed. When he goes into shed bump up the humidity to 60%-80% If you are using a Under Tank Heater it needs to be regulated by a thermostat so your snake doesn't receive burns. (UTH can get very hot I've seen some at 110+)