Align multiple indents

"I did not build this form so not sure how the line to the left was created"

They probably used an underscore leader in the first tab defined. This adds as many underscore characters that will fit up to that tab. Like so:

(in my example. My indent is set at 6p, my first line is set at -6p, and my first tab for the "line" is set at 5p with the underscore leader set)

This will work fine as long as you don't use a list automatic numbering.

It could work if InDesign allowed a tab character before a number in their number list options, but sadly it does not.

Sooo, alternatively, here's my jerry-rigged solution if you do want to create an auto number list. Since the line was created out of actual underscore characters,  create a prefix to the number of exactly the same amount of those characters. (they are usually the width of an EN space, so you would need to uses 2 of them to fill 1 pica of space, so in my example i have 10 of them to fill 5p of space). I followed that with one EM space (green). This pushed my number over to the 6p indent.

 I also changed the trailing tab that would normally be in the list with an EN space. This helps space your numbers properly when you get to double digits and beyond.

IMHO there is a better solution than shown in your example (no extra tabs and no indent to here sign needed).

Just use the "paragraph rule above" in your paragraph style with numbering:

Sorry for the German UI

You'll need to define lists. See this InDesign Help article. See the section "Define Lists":

https://helpx.adobe.com/indesign/using/bullets-numbering.html