There are a few categories of particles that you may hear about if you pursue a future in the sciences, so we will briefly discuss some of them. In order to describe the relevance of one of these groups, the fermions, it is necessary to slightly extend the idea of the spin quantum number.
As of now, it was stated that each particle has its own spin but if several particles are added together their resulting spin number will not be the sum of the individual spin numbers. The proof or experimental evidence is far too complicated to make a general rule of how to determine this number. In any case the important thing to remember is that you can't simply add the spins of the particles that make up a new particle to get its spin number.
Now that we have a new definition of spin in mind, we can group particles in terms of their spin. Fermions are particles that have a total spin of 1/2, while bosons have a total spin of 1.
Hadrons are any particles made up of quarks. This is very broad and could include some Fermions or particles from other categories not yet discussed, but nevertheless this term is used often.
Baryons and Mesons are more specific types of Hadrons. Baryons are particles consisting of three quarks and Mesons are particles consisting of one quark and one anti-quark.