"Marie était en retard de deux heures." What grammatical structure is "de" acting as?

Question

And, if a "best-efforts translation" to English were possible, would "de" represent "late OF two hours", "late BY two hours", or "late SOME two hours"?Cheers, Alec

Accepted Answer

If you really wanted to stay as close to the French as possible, you could say: Marie was in delay of two hours.

Answer

Bonjour,
To supplement Chris's answer: de is a preposition
See link below to learn all about prepositions: 
preposition
I hope this is helpful.
Bonne journée !

Answer

Thank you both! Understanding what grammatical purpose "de" serves has been tricky, so to backwards engineer French sentences to understand the English equivalent allows me to study the grammatical function in my native language before returning to the French version.

Again, thanks for your clarifications!

Answer

Understanding what grammatical purpose "de" serves has been trickyI think "de" merits a lesson all of its own, the numerous different functions can be confusing for English learners.

Answer

Bonjour Anne,Thank you for your suggestion! It has now been added to our to-do list. Merci de votre contribution !Bonne journée !