This is the 3252nd most frequent Russian word.
обычная
"Обычная" - "usual," "ordinary," or "common."
The word 'обычная' describes the noun 'работа,' indicating it is regular or standard.
Это обычная работа.
This is regular work.
The word 'обычном' is the instrumental case of 'обычная,' modifying 'кафе' to signify it is a standard café.
Мы встретились в обычном кафе.
We met in a regular café.
The word 'обычное' is the neuter singular form of 'обычная,' describing the noun 'платье' to show it is a typical dress.