The five instrument families are instruments that can be played together to create more sounds and harmonies. These five instrument families would include stings(orchestra), woodwind(flute, clarinet, oboe, saxophone, and bassoon), brass(tuba, euphonium, cornet, trumpet , trombone, flugel, horn, etc), keyboards, and percussion(snares, marimba, bass, bell, cymbals, etc).
All these instruments are used to make different sounds and music, or even for sound effects. Everything fits like a puzzle, but they can also be solo, these instruments don't always have to be played together.
I hope this is good enough to get you a passing grade ヾ(￣▽￣) Bye~Bye~