I just generate a default hexo site (do not add/remove any code), but I find that "categories", "tags" and "about" is not shown on the menu at home page as default settings.
I have already add "tags" and "categories" on the default content page, and they are shown on the home page.
I have searched a bit and could not find a solution regarding how to enable them. Could anyone help on this pls? Thank you.

I have found answers to the question. It will depend on the specific themes used in Hexo, i.e. when loading a theme in Hexo, then enable the "categories", "tags" etc items in that theme.
The general step is (take categories as an example): Run
Then a folder called "categories" will be created under root dir of Hexo/source/categories.
Revise the index.md file to let categories page show whatever you want.