We can quickly view the SharePoint online management shell version using below command
Get-Module *Sharepoint* | fl
In addition, we can see the version number of this file to know the SharePoint Online Management Shell
C:\Program Files\SharePoint Online Management Shell\Microsoft.Online.SharePoint.PowerShell\Microsoft.Online.SharePoint.PowerShell.dll
Why it is required?
Microsoft may say that few things will work only on a particular PowerShell version. So better to know which version of the SharePoint Online Management shell you are using.