You can view each team member's weekly capacity when sorting by Assignee in the Kanban board. To see this detail, sort your Kanban board by Assignee and turn on the option to display column totals.
To add your capacity, head to your profile from the side menu and edit the Capacity section.
If you're an admin, you can add the capacity for others as well by going into your side menu opening Settings, click on Colleagues, and edit their profile to update their capacity.
You will then be able to view the capacity of each team member.