Every time this question gets asked, the answer is the same. zero to a million. But honestly, having a dedicated website doesn’t matter for your actual sales; that happens through stores, outlets, etc. like Amazon, Barnes & Noble, Apple Books, indie bookstores, etc. If you’re selling your book it should be available all those places, and your website just has links to how to buy it. Promotion is a big subject. But in general, you’re going to need to know who your audience is and how best to target them directly. It’s very different for different kinds of books, so I can’t be more specific without more information. Your audience is not “everyone.” It’s “romance readers” or “science fiction readers” or “young adults” or “mystery fans” … but whoever it is, there will be specific channels to reach them. You need to find those and invest in your promotion, as much as you can, PRIOR to and AFTER publication. You need a pre-launch plan, a launch plan, a post-launch plan, and a maintenance plan.
I think the video is quite good. I'm not sure whether I'd like to post it or not, since it's sort of a personal experiment for me, and I don't think anyone else could possibly have as much time and expertise on hand.