This is the 122nd most frequent Russian word.
стало
"Стало" – "became" or "has become."
In this sentence, "стало" is used as a past tense conjugated form of the verb "становиться" (to become), indicating a change in condition.
Вдруг стало холодно.
Suddenly it became cold.
Here, "стало" expresses a transition to a more comfortable or pleasant state, reflecting a change in atmosphere.
После ремонта стало уютно.
After the renovation, it became cozy.
In this context, "стало" conveys a realization or a state of understanding becoming apparent over time.