Latin to English

I'm puzzled.

quae is the relative pronoun "who", "which", "what" or "that". It can be
the feminine nominative (singular or plural) or the accustive nominative or
accusative (plural).

postulas means "you need" or "you require"

praestes is the nominative singular "keeper"

But they don't seem to me to fit together grammatically. Perhaps I'm just
missing something. Can you provide any context?