In the category of multi-class mutual funds, this is the class that is generally characterized by a loaded fee structure. Class A mutual fund units will normally have a front- or rear-end load, to reimburse for the sales person's commission. Not all fund companies go after this class structure; though, it is the well-known method of distinction.
Characteristically, the class A fund has a lesser management expense ratio as compared to the other classes inside the same family. This is because of the load that is further added to the acquisition cost, or redemption.