I want to Setup the Ionic 4 Firebase database App.I followed the same steps https://devdactic.com/ionic-4-firebase-angularfire/ but when enter data in the app it do not appear int the https://console.firebase.google.com database.why?
You may have better luck asking the author, since you’re following that tutorial 
the author did not reply
Then it would be better if you add more information: what have you tried, what it worked, what it didn’t, if you have set up your Firebase credentials, if you have tried saving manually to the database, if you get any errors in the console, etc. I doubt anyone will read the whole tutorial and then wonder why isn’t working for you.
Be respectful of others time and make it easy for them to help you. That way you will get a lot more answers!
EDIT: You asked Simon 26 minutes ago, on a Sunday. Be patient and give people time to answer!
I’m sorry but that is hilarious