"Instead of nesting definitions" in docs

On this page: https://react.dev/learn/your-first-component

When a child component needs some data from a parent, pass it by props instead of nesting definitions.

all of a sudden, it says, "instead of nesting definitions". Can you explain in the docs more what is "nesting definitions" and how does it work to "attempt to pass some data and doesn't work or shouldn't be done"? I have never heard of "nesting definitions" after working with React for a few years.

Commencez par la page “Your First Component” à l’adresse https://react.dev/learn/your-first-component et repérez la phrase contenant “instead of nesting definitions.”. Consultez la page liée “Passing Props to a Component” pour le contexte, puis clarifiez ce que signifie imbriquer des définitions et pourquoi les props sont privilégiées. Le travail est terminé lorsqu’un utilisateur de React peut comprendre cette formulation et les indications prévues pour transmettre des données.