Simplify the following text for a Grade 9 native English-speaking person.
Original: The wine produced is then fortified by the addition of a neutral grape spirit 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 .