The noun sexuality can refer to sexual matters of all kinds. It often describes having sexual feelings. A novel about a teenager growing up may examine the awakening sexuality of its main character.
Sexuality also describes a person's sexual preferences and orientation — meaning whether you're gay or straight. Sexuality can refer to erotic experiences, but it can also be used broadly to refer to how organisms — whether human or animal — reproduce. There are scientists who exclusively study sexuality, from the mating habits of animals to the peculiarities of how humans pair up.