The accounting needs of a business can be quite different from that of a person. Businesses have customers that owe money, vendors which are owed money, employee payroll, more complex tax laws, etc. GnuCash offers some business oriented features to help facilitate these needs.

Accounts Receivable (A/R) and Accounts Payable (A/P) are used by businesses to record sales for which they are not immediately paid, or to record bills that they have received, but might not pay until later. These types of accounts are used primarily when you've got a lot of bills and receipts flowing in and out, and don't want to lose track of them just because you don't pay/get paid right away. For most home users, A/R and A/P are too complicated and confusing to be worth the effort.