$data = Import-Csv -Path "C:\Users\eeckert\Downloads\NoteVault licenses.csv"

foreach ($set in $data) {
    $userCode = ($set.'Assigned User').Substring(0,($set.'Assigned User').IndexOf(('@')))
    $set.Office = $userCode | Get-ADUser -property office | select office



}

$data | Export-Csv -Path "C:\Users\eeckert\Downloads\NoteVault licenses.csv" -NoTypeInformation