I hope you don't mind my asking, but won't your teacher explain these to you? Don't you have a book that explains these?

Here are some general ideas. These aren't technically perfect definitions.

Concrete: things you can see and/or touch; objects
house, table, person, cupboard, tree, bird, field, mountain, star

Abstract: not concrete, not objects
faith, love, tranquility, difficulty, electricity, fury

Collective: groups of things, animals, people
gang, committee, family, team, flock, herd,

Compound: two words stuck together
blackboard, greenhouse, skylight, lighthouse, shoehorn