Can someone explain “Funding Rate” in layman’s term?

Okay. I’ve come across a new term called “Funding Rate,” and I believe I understand the premise that it determines overall trader sentiments, whether bullish or bearish.

However, I find it difficult to understand what these lines quoted below means and how the “LONG pays SHORTS and vice versa” is related to maintaining the closeness of the futures price and spot price (or index price?)?