Hey there, and welcome to using Firebase.
If you have reached the maximum number of connections to your database, subsequent connection attempts will be rejected by the server. Once a connection becomes available again, the next connection request will be accepted.
If you are storage capacity, requests to write data will be rejected. If you're at bandwidth capacity, rejects to read data will be rejected.
Such questions and many more are also covered in our
FAQ, so I recommend keeping that handy as you start getting familiar with Firebase.
puf