This means that no money (or money’s worth) is given by the buyer (or on their behalf) to the seller, and there is no other consideration which has a monetary value.
Mae hyn yn golygu nad oes unrhyw arian (na gwerth ariannol) yn cael ei roi gan y prynwr (neu ar ei ran) i’r gwerthwr, ac nad oes cydnabyddiaeth arall gyda gwerth ariannol.