Isso é explicado um pouco mais acima no SRD :
Modifiers: Settlements possess six modifiers that apply to specific skill checks made in the settlement. A settlement’s starting modifier values are determined by its type. This value is further adjusted by the settlement’s alignment, government, qualities, and disadvantages. Note that introducing settlement modifiers to your game will somewhat increase the complexity of skill checks by adding a variable modifier each time the PCs visit a new town or city—consider the use of these modifiers an optional rule.
O tipo aqui é o tamanho do assentamento (Thorpe, Hamlet, Village, etc).