Using tags, you can group your workspace members from the Workspace Members page. To go to the Workspace Members page, click on your profile image at the top right and select your workspace.

You can tag members based on their location, roles, or anything else you like—iOS Developers, London, QA, to name a few examples. Select members by clicking and dragging, and use the "Add tag" button up top.

Using the tags you've created, you can filter the member list to a specific group:

You can also invite groups of users to your projects with one click.