Asexuality is a sexual orientation. Unlike heterosexuality, where people are sexually attracted to the opposite sex, or homosexuality, where people are sexually attracted to the same sex, asexual people are not sexually attracted to anyone. It’s not an inability to have sex, it’s not celibacy or abstinence, it’s not a temporary “dry spell”, and it’s not a fear of sex.
If you’d like to learn more, you’re at the right place. This site is all about asexuality. I’d reccommend starting with “Q & Ace: An Introduction to Asexuality“, then branching out from there.