You may be using cloud accounting software such as Xero or Quickbooks on your desktop PC. But there are also “apps” that mean you can do a lot of work easily whilst out and about.
This is especially useful for example when at a customer – why not raise the invoice there and then whilst still on site using your phone? How about reconciling your bank account before you get out of bed in the morning?
Take a look in the various app stores now.