Confused about firewall-what does it do really?

For years, since early betas, I was under the impression that the firewall settings for each application are about allowing/blocking outgoing traffic or any connection related to that application.
Today, on the play store, I see this description:
“Firewall (rooted devices only): Blocks hackers from getting in”
Huh?

Hi cooby,
thank you for your question! You’re right and you exactly described purpose and functionality of our firewall. I agree with you that description in Google Play could be little bit unclear.

We thought the same thing - when you block internet traffic of any app, you prevent to send any sensitive data to intruder or you block backdoor into your device.

We gonna clarify it, thanks for your feedback!