This is the 182nd most frequent Danish word.
indtil
"Indtil" means "until" or "up to" in English.
Here, 'indtil' is used as a conjunction, specifying the time frame until the action 'du kommer tilbage' occurs.
Jeg venter her, indtil du kommer tilbage.
I will wait here until you come back.
In this usage, 'indtil' is a preposition, indicating the limit in time, which is 'frokost'.
Lad os arbejde indtil frokost.
Let's work until lunch.
Here, 'indtil' highlights the extent of time up to a specific moment, 'nu'.