Check out the pinned thread in here and a good starter is The Ball Python Manual. My suggestion is to read the pinned caresheet and read the book together. That way, your both educating yourselves and learning together.
But to give you an idea, pending on sex P. regius gets around 3.5-5ft. Females can exceed 6, but its concidered rare IMO. An adult would approx be as thick as a coke can for exp in girth.
BTW, when my male exscaped, my mom was convinced to would eat our cat! LOL! Although she prolly wouldn't mind if it tried to swallow me instead. Less she has to see frozen furry rats in the freezer.