This is the 753rd most frequent Czech word.
nebyly
"Were not"
Here, 'nebyly' is used as the past-tense plural form of 'to be' (negated form). It references the conditions which is contextually plural.
Byli jsme na výletě, ale podmínky nebyly ideální.
We went on a trip, but the conditions were not ideal.
'Nebyly' conveys the negated past tense indicatory that the objects 'detaily' (details) were not displayed.
Na těchto fotografiích nebyly zobrazeny všechny detaily.
In these photographs, not all details were shown.
The word 'nebyly' describes the negation of satisfaction in the past, concerning a group.