As a Noun:
1. A person who reports the misdemeanours, true or fictitious, of their friends, peers, relatives, etc. English = telltale, informer, pimp. Informal English = dobber.
2. A person who tells other people things that you did not want them to know. Informal English = blabbermouth, big mouth.
3. Especially in the Catholic religion, a religious act in which you tell a priest about your sins and ask for forgiveness. English = confession.
As a Verb or Adjective:
1. To report the misdemeanours, true or fictitious, of your friends, peers, or relatives. English = tell tales, inform, pimp. Informal English = dob, dob in.
2. To reveal secrets. English = blab.
3. Especially in the Catholic religion, to tell a priest about your sins and ask for forgiveness. English = confess.