It's the indefinite article to nouns of male and neuter grammatical gender. For example "ein Buch" means 'a book.' It also can translate as one.
Eine stulle is a loaf (of bread)
An orange is: "eine Orange" or "eine Apfelsine" in German..
Ich bin eine... - I'm a... I have no idea what a marbnette is supposed to be, it's not a German word.
I have an "alpha" in my pants
eine Nische zu schnitzen is the translation in German. It is translated from English to German. German is mostly spoken in the European countries.
eine Quaste or eine Troddel
A charity is eine wohltaetige Organisation or eine wohltaetige Gemeinschaft.
Kneipe, or eine Kneipe, is the German word for a pub.
eine Villa
eine euro
Eine Uhr.
er ist ein = he is a... (sentence fragment)