PB: Stands for Peanut Butter, a generic term referring to a filler paste made using various fillers to get the consistency needed for a specific application, most often the 'thickness' of actual peanut butter. Hairy PB is made w/ 1/4" milled fibers and is for structural work, like installing transoms and stringers in a fiberglass boat.
PL: PL Premium is a 'type' of liquid nail that is polyuethane based
CSM: Chopped Strand Mat, fiberglass. Available in various weights, 1.5oz is typical for fiberglass boats, and is used in combination w/ 1708 fiberglass to rebuild a glass boat. Ideally, it's designed to work w/ polyester resin, but some is compatible w/ epoxy too. To get a better bond between layers of glass or to other previous layers (or the original glass hull) CSM is often used as a barrier layer. As mat, it takes a good bit of resin to be fully wetted out, and by being resin rich, it keeps the substrait and 1708 from wicking resin away from the layup and creating a weak bond. To add a little extra bulk or strength, some use CSM w/ epoxy on the plywood on their aluminum boat builds.