This is the 14010th most frequent Russian word.
обычный
Usual; ordinary.
Here, 'обычный' describes the noun 'день' (day) and means that it was typical or not exceptional.
Это был обычный день.
It was an ordinary day.
In this case, 'обычный' refers to the noun 'доме' (house), indicating it is typical or standard rather than fancy or unique.
Он живет в обычном доме.
He lives in a regular house.
Here, 'обычное' modifies the noun 'дело' (thing), meaning it is something familiar or frequently occurring.