Workspaces are company-wide accounts. As a user, you may have access to different workspaces from the same login.
To switch between workspaces, use the "Workspace" button in the top right of the dashboard. If you don't see that menu item, it means you do not have access to multiple workspaces.
When you choose a workspace, your entire session will be switched, so you cannot use more than one workspace at the same time in different tabs. If you do need to look at multiple workspaces simultaneously, you can open different browsers, or use incognito windows to have different sessions at the same time.