I like to think of it as a big list of extremely complicated instructions that you can follow to see how different types of particles interact in the standard model.

There's a lot of different phenomena that you can derive from it, but my favourite is that if you know what you're doing, you can just read possible interactions off of it.

It's also unnecessarily complicated, I've never seen someone have to use the full thing, you can get rid of a lot of it when you only care about specific particles. Part of the complication is that it's some insanely dense notation, it's actually far larger than it appears and contains lots of really complicated mathematical objects with some wild properties.

(And to the pendants, yes this is an equation for quantum fields and not particles exactly, but that's never easy to explain)