customization – Custom admin menu items

I’m very new to WordPress, familiar with CMS though.
I am taking over someone else’s wordpress website, by comparing with other wordpress, I found this one has some admin menus that the other doesn’t have, as the picture below shows
enter image description here

Are these coming from some plugin? I can’t find a plugin in this site that looks like it is related to these menus. Is coding needed to add these custom menu items?