Original: The wine produced is then fortified with the addition of a Brandy ( distilled grape spirits ) known as Aguardente in order to stop the fermentation , leaving residual sugar in the wine , and to boost the alcohol content .
Simplified: The wine produced is then fortified with the addition of a Brandy ( distilled grape spirits ) . This is done to stop the fermentation leaving residual sugar in the wine and to increase the alcohol content .