The par value refers to the amount that the issuer of a bond is supposed to repay the holder at or by the maturity date. It is also known as principal value, face value, redemption value and maturity value. If the par value of a bond is $5,000 it means that the issuer of the bond will have to pay back the bondholder $5,000 before the maturity date of the bond.
Bond prices are quoted as a percentage of par value. A $10,000 bond selling at "95" means that the market price of the bond is $9,500. A bond may trade above or below its par value.