New to PowerShell, but not programming. very confused

I have no idea what version of PowerShell I am running, but I am using Win10.

PowerShell newbie just trying to understand how things work. Many of years experience scripting SQL database stuff.

Here is my setup:

create table AA_ToddPS
(
Tseq int,
Tnum int,
Tstr varchar(40)
)

Insert into AA_ToddPS (Tseq, Tnum, Tstr)
Values (1, 711, 'Birthday'),(2, 721, 'Anniversary')

Select * from AA_toddPS

Tseq Tnum Tstr
1      711    Birthday
2      721    Anniversary

Here is what I have cobbled together from various sources:

## Just the User tablerows
$query = "SELECT Tseq, tnum, tstr FROM grain.dbo.AA_TODDPS order by Tseq"
$seqquery = "select max(Tseq) FROM grain.dbo.AA_TODDPS"

$seqnew = 0
$seqnew = invoke-Sqlcmd -Query $seqquery -ServerInstance 'WME-VM10-RW'
$tablerows = invoke-Sqlcmd -Query $query -ServerInstance 'WME-VM10-RW' 

## build a "data" table
$Datatable = $Null

$Datatable = New-Object System.Data.DataTable

$Datatable.Columns.Add("Tseq", "System.Int32") | Out-Null
$Datatable.Columns.Add("Tnum", "System.Int32") | Out-Null
$Datatable.Columns.Add("Tstr", "System.String") | Out-Null

$count = 0
foreach ($row in $tablerows)    
{
    $row = $Datatable.NewRow()

    $row.Tseq = $tablerows.Tseq[$count]
    $row.Tnum = $tablerows.Tnum[$count]
    $row.Tstr = $tablerows.Tstr[$count]

    $Datatable.Rows.Add($row)
    $count += 1
}

$count = 1
foreach ($Row in $DataTable.Rows) {
    $insert = "insert into grain.dbo.AA_TODDPS (tseq, tnum, tstr) 
               Values({0}, {1}, '{2}');" -F ($seqnew), ($Row.tnum + ($count * 100)), $Row.tstr

    $result = invoke-Sqlcmd -Query $insert -ServerInstance 'WME-VM10-RW' -OutputSqlErrors $true

   write-host "$result"
   $count = $count + 1
   $seqnew = $seqnew + 1
  
}

What I am anticipating is that when I hit my breakpoint at line 36, I would expect $insert to be

insert into grain.dbo.AA_TODDPS (tseq, tnum, tstr)

         Values (3, 921, 'Anniversary')

What I get is this:

$seqnew is just a variable, but has it been morphed into some object? I am not tied to using this setup to get this done, I just want to have it work, and to understand why.

Thank you for your time.