What is parent-child coupling in react and how does it relate to context?

I was reading the Context > Parent-child coupling documentation of React. I was unable to get what parent-child coupling from the documentation. Typically this line :

By passing down the relevant info in the Menu component, each MenuItem can communicate back to the containing Menu component.

The code is:

<Menu>
  <MenuItem>aubergine</MenuItem>
  <MenuItem>butternut squash</MenuItem>
  <MenuItem>clementine</MenuItem>
</Menu>