do I have a vpn with my Firefox browser?

Only the desktop Firefox currently has a built-ion VPN. https://support.mozilla.org/en-US/kb/built-in-vpn

It may be coming in next while on Firefox for Android though not for Fx 152.0

https://www.firefox.com/en-US/whatsnext/?tags=android

Looks like the Firefox for Android is getting a experimental built-in VPN in a progressive rollout testing as the KB article for it is live as of July 14. https://support.mozilla.org/en-US/kb/mobile-android-vpn