How do I read engine score?

When looking at engine output I see something like +0.30/+0.11.  I realize that the score is in units of pawns, and relative to white so that negative scores are good for black.  But here is my confusion:  What is the / for?  Sometimes the engine gives me two scores separated by a / and sometimes it gives me 10 scores in pairs, each pair containing a /.  How do I read that?  Is the first number the mainline score?  OK, what is the second number for?  

I've searched the internet, asked ChatGPT, and still cannot find a clear answer to this.  Please help.

https://support.chess.com/en/articles/8379354-computer-evaluation-numbers-on-chess-com-like-2-25

Thanks for the link, but it only addressed the part I said I already knew. Please read my original question and address the part I do not understand.

As far as I'm aware there is nowhere on site that does what you're describing for evaluation. Do you have a screenshot of what you're seeing?

Here is a screenshot.

Any ideas?

That was imported in from an external annotation as far as I'm aware.

That said, it's the evaluation before the move / after the move

Thank you!