This is the 4215th most frequent Catalan word.
estarien
"Estarien" means "they would be" in English.
This usage of 'estarien' is to form a conditional progressive tense, indicating a hypothetical or conditional state of being.
Els nens estarien dormint si no fos pel soroll.
The children would be sleeping if it weren't for the noise.
Here 'estarien' is used as a conditional form of the verb 'estar' to question about a hypothetical state or feeling.
Estarien contents amb aquesta decisió?
Would they be happy with this decision?
In this sentence, 'estarien' expresses a hypothetical action in the conditional mood dependent on another hypothetical condition.