When the new wine ferments and expands, it breaks the old skins because they can no longer stretch out. Jesus' audience would have understood the information about the wine's fermenting and expanding. (See: [[rc://en/ta/man/translate/figs-explicit]])
This can be stated in active form. Alternate translation: "the wine would spill out of the bags" (See: [[rc://en/ta/man/translate/figs-activepassive]])