Usually it refers to the ability to solve problems in a practical way, but in order to do that a person needs a solid base of common knowledge about the environment (social and physical) in which they live. This kind of knowledge is often absorbed unconsciously while growing up, but there can be numerous reasons why some people miss out on acquiring it.
People from rural backgrounds will lack street savvy if they move to the city. City people who move to the country won't have a clue about slowing down in a car when passing a horse and rider on the side of the road, leaving a gate as they found it, keeping dogs on leashes, planting plants that become environmental weeds, or how to fix a fence or maintain a tractor. Their country neighbours will perceive them as having no common sense.
