This is the 257th most frequent Estonian word.
järgmise
"Järgmise" means "next" in English.
In this instance, 'järgmise' is in partitive case, showing the object of the action (waiting for the ‘next’).
Ootan järgmist posti.
I am waiting for the next post.
In this sentence, 'järgmise' is in the genitive case, modifying 'peatuse' (stop), indicating the next item in sequence.
Läheme järgmise peatuse juurde.
We are going to the next stop.
Here, 'järgmise' again is in genitive case, modifying 'nädala' (week), to denote the ‘next’ entity.