"You are drinking your coffee."
Translation:Du drikker kaffen din.
As a guideline, the possessives "sin/sitt/si/sine" are used to say "its/her/his" when "it/she/he" is the subject of the sentence/phrase, e.g.,
"Astrid har kaffen sin," or, "Hun har kaffen sin." (Astrid/She has her [own] coffee.)
In the case of I/my it is
jeg - min/mitt/mi/mine.
For the singular you/your, it is
du - din/ditt/di/dine.
The form of the possessive that has the "e" on the end (sine/mine/dine) is used when that which is possessed is plural, e.g.,
"Du elsker barna dine." (You love your children.)
ahh yes I was also confused about en, ei and et ... I assumed they serve das 'a' and 'an' purpose that comes with vowelic sounds in english words.... but I couldnt figure out for which sounds they use en or which sounds they use et..... so Tusen Takk for clearing up misconception again :)