First; just 'cuz the house is sold as-is doesn't mean you can't have it inspected; it just means you can't use that info to bargain with. A good home inspector can help you detect problems and make a list of fixes for when you're the owner.
The house i grew up in had something like that. My dad called it the trap. Not to scare me, but because (he said) it could trap water that may get into the basement. I'm sure someone here will chime in with a more technical answer, but I see a cleanout for your main drain and access for your water supply. Although it is not a sump, I've heard that a "trap" can relieve any hydrostatic pressure under your basement floor, and allow standing water a place to escape.
