Determine last time that AD has synced with Office 365

Check the event logs on the server, it holds entry for each time the sync process runs.

Can you provide me with a PowerShell command that will display this information?

I would rather be able to type in a PowerShell command to get this info rather than sorting through the event logs.

Have you tried Get-EventLog?

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/get-eventlog?view=powershell-5.1

What is the exact syntax of the Get-EventLog command that I can use to determine last time that Server 2016 Active Directory has synced with Office 365?

I don't currently have an AD server for testing/comparison.  But you can try this as an example.  The events you are looking for will either fall under the application, security, or system for LogName, if you can force a sync and then check those logs then you'll likely be able to find a good Source and Message string.

Get-EventLog -LogName Application -Source WinMgmt -Message "*event*" | out-host -paging

Select allOpen in new window

I included the "out-host -paging" to ease the process as it performs a "page/more" type function.  Cheers!

What events in particular should I search for while using the PowerShell command listed above?

You might find these useful

https://blogs.technet.microsoft.com/dkegg/2017/01/12/aad-connect-event-ids/

and for troubleshooting

https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnect-troubleshoot-sync-errors

These articles are great.

However, does anyone know what the exact PowerShell command or PowerShell script is that will tell me the exact date and time that AD has last synced with Office 365 or with Office 365 Azure?

You should find Get-MsolCompanyInformation has what you are after.

This is an O365 powershell command