It is roofing material that comes in a roll. Usually 50 or 100 foot rolls and is can be 36" or 48" in width.
This is an old material used on fair/poor quality homes or garages etc. in the past. It was/is an asphalt or fiberglass material and is simply rolled across the roof and nailed much like regular shingles.
ASPHALT ROLLED ROOFING: Asphalt rolled roofing is made of the same material as asphalt shingles. It typically comes in rolls that are 18 or 36 inches wide.
Rolled roofing is usually installed on sloped or flat roofs. It can also be found in roof valleys. The material is considered to be of low quality with a life expectancy of 5 to 15 years. Warping and buckling due to expansion of the material is a common problem. The granular coating tends to break down quickly in the wrinkled areas resulting is localized wear and deterioration.
Periodically inspect rolled roofing for granular deterioration.
If installed in roof valleys, check for cracking, tearing, and deterioration.
Be sure all overlaps, edges, and surface nails stay well sealed.