To find the number of billable users and invites in your Organization, go to the Manage Organization and Workspaces Dashboard (click on your company's logo in the upper right corner, then click on View All Workspaces). Once there, click on Manage Organization and Workspaces.
At the top of the first column in the table, you'll find the total number of billable users and invites in your Organization (the number will be larger and bolded).
You’ll also see a list of all the users in your Organization. Active Billable Users (Admins, Owners and Members) are shown in bold. Non-Billable Users (Disabled or Observers) are shown in italic.