A bank rule suggests a category for downloaded transactions that meet stated conditions. Define whether it applies to money in or money out, then choose description or amount conditions and the category. All conditions must hold when you choose All; Any accepts a line when just one condition holds. Review suggested transactions before allowing automatic posting.
A broad condition can catch the wrong payee. A rule containing Harbor may match both a utility company and a supplier. Use the distinctive part of the description, and test examples that should match as well as examples that should not. Money direction also matters: a refund from a vendor should not be treated as another expense payment.