A department is a named group of agents (Sales, Support, Billing) with its own queue, business hours, routing rules, and analytics. Every workspace can have any number of departments.
Create one
Settings > Departments > New. Name it. Pick a color (shows up in the inbox). Add agents (or import them from a CSV). Save.
Route by channel, page, or tag
Routing rules can match channel (chat, email, phone), the page a chat started on, business hours, customer tags, or any custom condition. First-match wins.