There is a job in most offices that nobody would describe as a job if you asked them to. Somebody opens two windows, reads a number out of one and types it into the other, four hundred times. They are careful, so it mostly goes right, and the mistakes surface a month later in a reconciliation.
AI staff take that job over. The agent looks at the screen the way a person does, finds the field, clicks it, types, reads back what happened, and moves on. Because it works through the screen, it can use your system whether or not it has an API, whether the vendor still exists, and whether it is a web portal, a Windows application from 2009, or a remote desktop on somebody else's network.
Two things make it safe to run on a real business's systems. Control is leased: if a person touches the mouse, the agent is locked out until control is handed back, so it can never fight a human for the keyboard. And every action is written down, so an entry from three weeks ago is a log line you can read.