Kindergeld decision from the Familienkasse
A Bescheid is a letter in which an office decides something about your case.
What you can do
If you disagree, you can file an Einspruch.
Say which Bescheid your Einspruch is against, and sign it.
File the Einspruch in time, even if some documents are still missing. Keep proof that it arrived.
If you do nothing, the Bescheid usually becomes final when the deadline ends.