What exactly is the service locator pattern? [duplicate]

I got told to open a new question with one focus (which this is) as my old question was closed, you can take a look at it for referencing.

Search engines return comparisons and context, but no explanation. YouTube returns a collection of poor quality videos with more dislikes than likes.

The closest answer I found was this stackexchange question, but it just talks about using dependency injection, composition root, using service classes, why it is an antipattern, etc etc.

All of this can be confusing... when you don't even know what it is... I come from a C# background so I need an example in C#.