What does the phrase "friends with benefits" mean?

What does the phrase "friends with benefits" mean?

Lillian Glass (Communication Psychologist) gives expert video advice on: Is it possible to have more than one soulmate?; How do I decide if I want to date casually or seriously?; How can I make better decisions about whom I date? and more...

"Friends with benefits" is a term that's gotten a lot of popularity lately. It's a term that says you have a good friend, you're connected, but there are some benefits - and they oftentimes include sexual benefits.