Assigning clients to your employees allows them to work only on the documents of the clients you choose.
Employees will only see the documents of the clients they've been assigned.
Go to the Clients menu
Click on a client
Under Assign collaborators, click anywhere in the Select box
Choose which employee(s) you want to assign to the client ( your employee has to have a user access to the console ( you can check it in "users" menu)
Save.