Help with a line of code

I got this snippet of code from another script that someone had written.  I have a script that emails managers of users who have not logged on recently to ask where they are and I wanted to put the number of days since they last logged in.

$Numberod=Get-ADUsercadcscw-PropertiesLastLogon|Select-object @{E={$($(Get-Date) - $([DateTime]::FromFileTime($_.LastLogon))).Days}}

write-host"Not logged in for $Numberod Days"

PS U:\> C:\scripts\GetDaysBetween.ps1

Not logged in for @{$($(Get-Date) - $([DateTime]::FromFileTime($_.LastLogon))).Days=128} Days

So I have two things, as you can see from the output I don’t get just 126 for $Numberod I get my whole hash array. I tried -expandproperty but that didn't work.

Second is, I don’t know what this bit is doing (well I do in some sense, it gets the number of days between the last logon and today)

@{E={$($(Get-Date) - $([DateTime]::FromFileTime($_.LastLogon))).Days}}

I know that @{ } encloses a hash table, Get-Date gets the date today and [DateTime] is a .net function, but I don’t know where that .net code is starting and finishing nor what :: does.  $_.LastLogon is the object I returned with the get-aduser command and piped to the next step

It looks like there is a bit of maths going on in this step

(Get-Date) - $([DateTime]::FromFileTime($_.LastLogon).

I know E is Expression but I’ve not used Expressions before so I’m not familiar with them. There are quite a few $ in there too. 

So if someone could tell what I need to do to get just 126 returned and if they could also explain what is going on I’d appreciate that.

Jonathan