French phrase
Je serai en retard de ~ minutes.
Meaning
I will be ___ minutes late.
When to use it
A brief notice that arrival will be delayed. It is used before the expected arrival time in casual to moderately polite situations.
Example dialogue
Je serai en retard de 10 minutes.
I will be 10 minutes late.
Pas de souci, je t'attends.
No problem, I'll wait for you.