The Jeep has some rust underneath the bumper and I think just mostly underneath the vehicle itself.
Rust under the jeep is a much bigger deal than rust on the body. Body rust for the most part is cosmetic and or easy to fix. Frame rust on the other hand can be structural. Best bet is always to bring it to a mechanic who can get it in the air and look it over top to bottom so that you know how much money you'll have to put into it.