Complex sentence: Winemakers will sometimes add acids to the wine (acidification) to make the wine more acidic, most commonly in warm climate regions where grapes are often harvested at advanced stages of ripeness with high levels of sugars, but very low levels of acid.
Split into simpler sentences: Winemakers will sometimes add acids to the wine (this is called acidification) to make the wine more acidic. Doing this is most common in warm climate regions where grapes are often harvested at advanced stages of ripeness with high levels of sugars but very low levels of acid.