In the bond world, par is the face value of a bond. That is, the par value is the amount the issuer promises to pay the bondholder when the bond matures. For equities, the par is a very small, arbitrary value assigned to each share.
Let's assume Company XYZ issues $10,000,000 in bonds to the public. It may do so by issuing 10,000 bonds, each with a $1,000 face value. That means that when each bond matures, the holder will receive the par value of $1,000. Most corporate bonds have $1,000 face values, but municipal bonds often have $5,000 par values and federal bonds often have $10,000 par values.
The par values for stocks are typically $0.01 per share and are set forth in the issuer's articles of incorporation. For preferred stock, however, par values may be higher because they are often used to calculate dividends.