When he issues a bond, he takes a piece of paper (perhaps not literally...) and stamps "Venezuela will pay bearer $1000 on 1 January 2025" (or whatever) on it. When he sells it, he gives the piece of paper to someone else and in return they give him money, theoretically the present value of the bond. The discount between the two amounts is mostly an indication of Venezuela's creditworthiness, but of course a portion of the difference is just a reflection of the discount rate for assets to be delivered in future. This is exactly the same as when any other entity issues a bond.
