The phrase "additional acres" means extra parcels or pieces of land. It refers to more land being included or added to an existing area. Full definition
This farm, which would eventually include 30 additional acres of surrounding land, was used as a shelter for lost, abandoned and abused pets. (waysidewaifs.org)
If funded, nearly 500 additional acres of highly productive farmland will be protected. (scenichudson.org)
Several large and as - yet uncontained wildfires have burned 1,500 homes and more than 53,000 acres in Napa County, as well as thousands of additional acres in Sonoma County — both of which comprise California's wine country. (businessinsider.com)