Adding tabs on your pages sections is important as it is the easiest way your readers or possible advertisers or sponsors can navigate your content. It is also the easiest way to sort out your categories for easy access.
About pages are essentials for new readers because they get to know you (the blogger/s) better and a little fun fact, about me pages are actually one of the highly-trafficked pages. In creating "about the blog or about me" pages, you can write there information about you but not too much, just basics because it's safe to put out too many on the internet. You can also write there your blog's background and goals.
CONTACT PAGE/ADVERTISERS or PR PAGE
If some of your readers want to have an intimate conversation with you, they can just go to your contact page to see your email address or the links to your social media. If you want some extra cash coming in, you can also set up a page for advertising infos.
If you have categories like I do, it's time to sort it out by adding some tabs on the navigation bar but just add your main categories or main niche/s. You can put your sub-categories or blog series on your sidebar.