GET AZURE AD USER SYNCHRONIZATION TIME

First you have to connect to MSOnline using your credentials:

$credential = Get-Credential
Import-Module MSOnline
Connect-MsolService -Credential $credential

Than you can get the attribute called LastDirSyncTime using the following command:

Get-MSOlUser -UserPrincipalName "tim.buntrock@domain.com" | Select-Object LastDirSyncTime