Some skills are particular to a certain class or sub-class of characters. A Rogue will know how and where, to Fence Stolen Goods, an honest citizen won’t. A Soldier or Sailor may know how to operate cannon, a Priest is not likely to have that skill. Someone outside of these classes will find it difficult to learn these skills without being a member of the class. Characters (of the right class) start play with SOME class skills at no cost. Specifically, each class, and sub type, have certain Inherent Class Skills that are native to their class and associate life style. Mystics know the tenants of their religion, soldiers know military protocol, sailors the fundamentals of seamanship and so on. Raising these skills beyond that starting level, or adding additional class skills, does cost skill points.
Both the Basic Skills and SOME Class Skills come at no cost to the starting character. (See the class and sub class descriptions.) Anything beyond that must be ‘bought’ using Skill Points. A 1st level character starts with X number of Skill Points, determined by their Class and their Intelligence, and gain more as they advance in levels.