Using older versions of Outlook for Mac for personal email and calendar
If you are stuck with the New Outlook, the following work-around seems to work: Suppose you want to know the total number of emails in your Inbox. Then with the cursor on the area, select ALL mails in inbox, then Drag ALL to the left sidebar and then back again (but don't actually drop them). During this maneuver, a number showing the total number of emails you are moving back-and-forth will appear for a second. (Alternatively, create a temporary mailbox to move to temporarily for the purpose of seeing that number, then move them back. Name the mailbox something like [0 a temp box] so it will be at the top for convenience.)
Not a real solution, but it's better than the pain of not knowing how many more emails you still have in your inbox.