What is the meaning of such construction in powershell

Question

Very newbie question. Found such workflow in MS Exchange script:

[CmdletBinding()]
param ()
begin {
    $scriptBlock = {
        function foo {
            # some code
        }
        foo
    }
}
process {
    Invoke-Command -ScriptBlock $scriptBlock
}

as i understand it is for running this script on remote hosts, but how? or there are any other reasons for such invoke-comand as a single call in process part? Or please sugest keywords to find more about this?

Here is full script: aka.ms/ResetScanEngineVersion