This is the 76th most frequent Hungarian word.
amelyek
"Amelyek" means "which" (plural) in English.
The word 'amelyek' is used as a relative pronoun to introduce a clause describing the books ('könyvek').
Ezek azok a könyvek, amelyek a polcon vannak.
These are the books that are on the shelf.
Here, 'amelyek' refers to the birds ('madarakat') and links it to the action of flying.
Láttam azokat a madarakat, amelyek a magasban repültek.
I saw those birds that were flying high.
'Amelyek' is used to detail specifically which pictures ('képeket') are being discussed.