Internetsexual is an attraction to people online, for example on social media. People who are iternetsexual can have long distance relationships. There is a big chance that if you meet that person in real life you're just not attracted to them anymore.
Other sexualities/genders
Internetsexual isn't connected to any gender or other sexuality, you can be heterosexual, lesbian, etc. It's just an extra term to identify yourself.