What is the best way to study the script using debugger vscode

Hello,
I need to study the following script. What it does and understand it.

SO I am using debug mode in Vscode, but when I click on “Step into”, it is skipping and not going into the next line. Perhaps something is wrong with my VScode?

What is the best way for me to study the script and see what it does? How to manually paste the blocks and study?

So I set the debugger on line 1
When I click the down error Step into, it jumps into the line 206.

For example, I need to understand what does this do? How would I accomplish this with the debugger or manual process. tried copying and pasting and still doesn't understand what it tries to do
gc $sidMappingsFile | foreach {

            $orgShell = $null
            $fields = "","",""
            $fields = $_.ToString().Split(",")

            if ($fields[2] -eq "True") {
                $sourcesid = $fields[0]
                $targetSid = $fields[1]
                $isprimary = $fields[2]
         

Thank you!