As a Noun:
1. A statement which you make to someone in which you say that you will definitely do something or give them something. You believe this statement to be true. English = promise.
2. The making of a true statement, particularly after having said things that were not true or at least not the whole truth. English = admission.
As a Verb or Adjective:
1. To say to someone that you will definitely do something and that you are telling the truth when you say so. English = promise.
2. To tell the truth about something, especially after having said things that were not true or having avoided telling the whole truth. English = admit.
Interactive:
1. Used alone, when you doubt the truth of what your addressee is saying, to mean you want assurance that it is indeed true. English = 'For sure?!', 'Are you telling the truth?!', 'No kidding?!', 'Are you for real?!' and so on.
As Modifier:
1. Used at the beginning of a sentence to mean that what follows is the truth, especially when it is an admission. English = to tell you the truth, truthfully; I admit it ...
2. Used to mean that what follows is the truth, giving the full details of a situation that may not have been stated by you or someone else yet. English = actually.