A client team allows you to set which colleagues work with specific clients. You can add colleagues or full teams to the client team.
You can view and manage the client team from any contact's Details tab.

Adding a Client Owner
If there is a specific person in your firm who looks after a client relationship or is responsible for the vast majority of their work, you should mark them as the client owner.

Adding a Client Manager
If there is a specific person in your firm who looks after a client, you can mark them as the client manager.
From the details tab of the contact's profile, you will see a section for the client team.
Clicking edit will allow you to choose a new client manager or an existing one.

The client manager is separate from the client owner. Both fields can be left blank if they are not relevant to your team.
These fields are most useful if you want to filter work items on your Kanban board by client manager or client owner. This will then show all work items for clients that are managed or owned by the staff member/s you identify.