A machine can carry out any calculation at all, however long. Punched cards tell it which operations to perform on which numbers. It keeps the numbers in a store, works on them in a mill, and chooses which cards to follow next by its own results.
The Analytical Engine needn’t stop at numbers. It works on symbols by rules, and symbols can stand for anything whose relations can be put into rules, like the notes of music. So it could compose music, or work in any field whose rules we can write down.