Translation:She is drinking a glass of white wine.
For those wondering why romance languages have the word "blanco" (or similar versions) for white, while english has the word "black" for black, it is because in ancient Proto-Indo- European, the ancestor of "blanco" and "black" meant "great light or flame" some people used the word to describe the light itself (blanco), while others took it to describe the ashes or darkness left behind after the fire went out. I find this very interesting.
blanc is a cognate with the English
blank. According to etymonline.com:
early 13c., "white, pale, colorless," from Old French blanc "white, shining," from Frankish *blank "white, gleaming," or some other West Germanic source (compare Old Norse blakkr, Old English blanca "white horse;" Old High German blanc, blanch; German blank "shining, bright"), from Proto-Germanic *blangkaz "to shine, dazzle," extended form of PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.)).
Old English blæc "dark," from Proto-Germanic *blakaz "burned" (cognates: Old Norse blakkr "dark," Old High German blah "black," Swedish bläck "ink," Dutch blaken "to burn"), from PIE *bhleg- "to burn, gleam, shine, flash" (cognates: Greek phlegein "to burn, scorch," Latin flagrare "to blaze, glow, burn"), from root *bhel- (1) "to shine, flash, burn;" see bleach (v.).
So it looks like ttri8915 was on the right track.
According to the "Tips and notes" (available on the web, if you're using an app) for the Da/De section:
DA AND DE
Although both da and de can be translated into English as of, they have different meanings:
Use da when you're talking about quantity.
Use de when talking about possession.
Note: the direct object -n ending (accusative) is NOT used after da or de.