This is the 18070th most frequent Russian word.
футбольной
"Футбольной" means "football/soccer-related" or "football/soccer's" in English.
The word 'футбольной' is used as an adjective modifying the noun 'formu' (uniform), indicating that the uniform is related to football.
Я купил новую футбольную форму.
I bought a new football uniform.
The word 'футбольной' is modifying the noun 'komandy' (team), specifying that the team is associated with football.
Мой брат - игрок футбольной команды.
My brother is a player of a football team.
Here, 'футбольной' describes the type of league in the noun phrase 'futbol'noy ligi' (football league), signifying its relevance to football.