Title/sub-title/header

Hi community !

I have a question and need your help : in order to have a good google referencing, I don’t want to make a mistake on this issue : I understand what is called a title, but I am not clear about what Sparkle calls a sub-title versus a header.

Title (H1): Cars
summary of the page juste bellow the title (H2): Cars are a symbol of social status we are discuissing in this page
1/ (H3)Tiny Cars
The market of tiny cars…
2/ (H3) Luxury cars
The market of luxury cars…

What is the short summary of the page just bellow the Title (H2, I guess): is it the sub-title or the header ?
Is H3 the sub-title ?

If one of you speaks French or is in France, I take it as I am not perfect in my English.

Many thanks

Sylvia

Capture d’écran 2021-09-07 à 16.33.11