The writing settings configure various options with regards to your site content.
Settings include defining the Default Post Category so if you don’t define a category what will it default to?
The Default Post Format which is nearly always going to be standard but if your Theme supports it, it could be something else.
If your site is predominantly about videos you might want to make it a video post format and if you are using a Theme such as, sorry a plugin such as a link manager you will also see an option here for the default link category as well.
If you do decide to install the Classic Editor plugin which allows you to use the Classic Editor rather than the Block Editor, you will see two extra options on this screen.
The default editor for all user’s option allows you to select the default editor to use. This can either be the Classic Editor or the new Block Editor.
If you have installed the Classic Editor plugin, then you will most likely want to select the Classic Editor radio button for this option.
If you have multiple Editors on your site (like, people), there is an option for allowing users to switch the editor option and they can choose which editor they would like to use.
Now if you allow your users to switch editors, their individual user profile page will show a new option that allows them to select between either the Classic Editor or the Block Editor.
But you should be careful because if one of your users or admin edits a Page or Post with the Block Editor and then another user or admin edits the same Page or Post later on with the Classic Editor, then you may end up causing issues with your content.
Especially if that first user re-edits the Page with the Block Editor again, there is a very good chance that you could lose content, or break Blocks within the Block Editor.
So, if the Page is added with the Block Editor, or an existing Page is converted to Blocks then it is best to continue in that fashion.
With regards to the Post via email, I can’t say I have ever seen anyone using this method and it just means that you can create a post using your email, and you would have to populate this information here, but to be fair it, is just as easy to log in and start writing and using the interface instead of using your email address.