What can accounting software do?

Account.

Make an accountant(or anyone) work faster and minimize errors,before those softwares came accountants and everyone else used to work like crazy sometimes all night,I know this because my dad was one,basically these would include making accurate and quick calculations around rows and columns,making graphs and charts etc. and almost everything accounting,the major advantage is how quick and accurate it is as compared with going manual

Add and subtract

Depends on your needs.