This is the 4554th most frequent Catalan word.
paller
A "paller" is a haystack or hayloft.
In this expression, 'paller' is used metaphorically to describe a large area or situation of overwhelming components.
És com buscar una agulla en un paller.
It's like looking for a needle in a haystack.
Again, 'paller' is referred literally to a haystack or barn area where hay is stored.
Els nens jugaven al costat del paller.
The children were playing next to the haystack.
Here, 'paller' refers to a physical haystack or storage for hay.