PowerShell: Need to get values between two lines/rows

Regex would be your best bet here, it seems.

$file = "data.txt"
$pattern = "---Start of Data---([\s\S]*?)---End of Data---"

$string = Get-Content $file -Raw
$result = [regex]::match($string, $pattern).Groups[1].Value

$result will contain the output that you want.

In addition to Yash's great answer, here is some fun stuff you can do with switch if you want to catch different parts or sections that are identifiable by some start and end line

$text = @'
Configure text Example
Configure text Example
Configure text Example
---Start Part A---
Data I want to grab
Data I want to grab
Data I want to grab
Data I want to grab
---End A---
Some other text that isn't needed
Some other text that isn't needed
---Start Section B---
Data I want to grab in B
Data I want to grab in B
Data I want to grab in B
Data I want to grab in B
Data I want to grab in B
---End B---
'@ -split '\r?\n'

$inside = $false
$pattern = '---(?:Start|End) ?(\D+?)---'

switch -Regex ($text) {
    $pattern {
        $inside = !$inside
        $section = $Matches[1]
    }
    default {
        if ($inside) {
            [PSCustomObject]@{
                Section = $section
                Line = $_
            }
         }
    }
}

Output

Section   Line
-------   ----
Part A    Data I want to grab
Part A    Data I want to grab
Part A    Data I want to grab
Part A    Data I want to grab
Section B Data I want to grab in B
Section B Data I want to grab in B
Section B Data I want to grab in B
Section B Data I want to grab in B
Section B Data I want to grab in B