It is the system used in the United States to measure the sugar content of grapes and wine.
Each degree of Brix is equivalent to a gram of sugar per 100 grams of must.
The system is named after its inventor, the German F.W. Brix, but German oenologists use a different scale called "Oechsle". Most of Europe (including France and Italy) and Australia use a similar method, called "Baumé" scale.
