Hi, bob95742, and welcome.
Your cruise price includes your stateroom, meals in the dining room or buffet, and nightly entertainment. I'm not sure about Carnival, but if they have any specialty restaurants, those will be extra. Certain drinks such as water, coffee, and I think iced tea are free. Soda and alcohol are extra.
Again, having not been on Carnival, I don't know if they charge for room service or not. There may be a fee for a late night delivery (between midnight and 5 am maybe, or something like that). There should be at least one pool open 24 hours for passengers to enjoy.
Also, the price posted on the Carnival website is before taxes and port fees. There's also gratuities, which you can either pre-pay when you book, or maybe just pay cash on the last night of the cruise. Check Carnival's website for the gratuity guidelines for Carnival. Again, I haven't been on Carnival, so I don't know what their guidelines are.
Be forewarned, cruising can be addicting, so if you step off the Splendor and want to book another cruise, don't say you weren't warned!
2007 - Majesty of the Seas
2009 - Enchantment of the Seas
2010 - Freedom of the Seas