Most of us have already read one or more of the Harry Potter books or watched one or more of the movies. Because of that, we already have an excellent understanding of who Harry, Ron, and Hermoine are as characters. However, it's still possible to go back and look at just their names to see what they can tell us on their own. Here's one reading of it.
First, look at Ron Weasley. It's a simple name, just three syllables, used commonly in places like the United Kingdom. That might tell us that Ron is a simple character. Indeed, that would align with who he's presented as throughout the series. Although Ron is a simple character, he's not a bumbling fool. He's a little weasely if you catch my drift. He's able to figure things out in the moment, weasel his way out of trouble, and act as a great sidekick to Harry.
Hermione Granger's name is more complicated than any of the other major characters' names. Hermione is a very unique name. This could speak to Hermione's intellectual side. She's shown throughout the series as being one of the smartest witches in the room at any given moment.
Because Harry Potter is the titular character, it can be difficult to focus solely on his name. However, when we do, I think we see a name that's more similar to Ron's than Hermione's. It's simple—not quite as simple as Ron's, though. Potter might be the more interesting part of the name. It calls back to when last names were sometimes used to describe a person's profession. If that were the case here, Harry would be a potter—someone who pots plants and the like. That's a humble, working-class job. I think given the usage of Harry, itself a working-class name, and Potter, Rowling wanted us to view her titular character as a working-class hero—not someone who was above the common person. Harry confirms this by the way he presents himself throughout the series.