Newton Alderman-at-Large
In short, an Alderman-at-Large covers the entire City of Newton.

Newton's Board of Alderman is comprised of 24 individuals.  A Ward Alderman from each of the 8 Wards and two Alderman-at-Large from each Ward.   A citizen of Newton gets to vote on his/her Ward Alderman and on all 16 of the Alderman-at-Large seats picking two for each Ward.

Greer is a resident of West Newton in Ward 3 and is running for one of the two Alderman-at-Large seats for that Ward.