This simply means polishing the language till it flows easily like a good conversation. Or like Hemingway put it: “Finding the right words and placing them in the adequate order”.
The best advice is to simply trust your ears. It was the love for language that led you to write the novel in the first place, so this is the time to trust your instincts.
If a sentence sounds too sophisticated or overly exaggerated then you must lower the tone or just remove it. If it sounds floppy, then it still needs work. But if a sentence flows without effort and transmits the exact meaning of an idea to us, of what we are looking for, then do not touch it.
In terms of style, in my opinion, the simpler the better, so it doesn’t attract attention (in comparison to the pompous prose of inexperienced writers). And the paradox is: the simpler the prose, the harder you’ll work on it.
Important: Don’t try to sell your novel to a publisher until you have spell-checked your words over and over and over (And then once more for good luck).
If you ask a hundred writers on how to write a novel, you’ll get a hundred different answers.
Everyone is unique and works in a singular manner. I can tell you what works for me and for many other writers that I have spoken to. But if you need to adapt the previous steps to your own needs, this is what you should do. The above-mentioned steps are a prototype: you must give them definitive form, which is yours to make.
Beyond the process of writing novels, it is important to practice, practice, and practice. Through the application of what you have learned, you’ll make progress on your first novel.