I'm reading a book on macroeconomics, and on a chapter on the money market, when explaining how the central banks(CB) determine the interest rate, there is a balance sheet for the CB. In it, under the assets we have bonds, and under liabilities we have currency and bank reserves. My question is which bonds are these? Do these bonds belong to the same country that the CB belongs to? Isn't in this case the bond of the CB a liability/debt that will have to be repaid in the future? Because if so, it seems that we're just exchanging one liability (bond) for another (money).
Or are these bonds from any entities other than the CB itself?
Any help would be appreciated.