My mom used one in the 70s and 80s for accounting and billing in our local village. As I recall although they had multiple terminals to access it these were shared, you didn’t have a terminal on the desk. You’d pick the application you were going to use from a text menu, enter your identifier (no password), and make your entries. Actual billing runs or other accounting runs were done in batch overnight. When they upgraded to AS/400s everyone had PCs on their desks and used 5250 terminal emulators to access the system over SNA/APPC.
It was a "minicomputer". Nowadays they are called "midrange" computers and nearly extinct. They were general purpose computers, used for all kinds of of operations/calculations.
Most minicomputers landed in companies/departments too small to afford a mainframe and where used for inventory, POS, bookkeeping, payroll, etc.
My school district got one; I assume they did accounting on it. RPG would be a good fit for accounting. But also, they taught programming to us students. I learned FORTRAN on one of these in 1979. 4K RAM and punched cards.
We had a System/36 at a family business, which was the ancestor of the AS/400.
It was a large box, roughly the size of a refrigerator on its side. It had 256K of memory, a whopping 100 megabyte disk, something like 8 terminals, and a couple of line printers. I think it cost almost $200,000 USD in 80's money.