You are not alone. UE4 Documentation is… well.
If you look up the documentation for most functionality you will get a single vague sentence that says something like this:
Thing’s Name
This thing does a thing to a thing.
Also here’s a screenshot of the thing for some reason. Bye.
Please direct your attention to MDN
https://developer.mozilla.org/en-US/…s/Array/splice
This is how documentation should be written.