This is the 5254th most frequent Russian word.
общественном
"Общественном" means "public" or "social" in English, depending on context.
Here, 'общественном' is used as an adjective to define 'движении' (movement), expressing its social or public nature.
Он всегда участвует в общественном движении.
He always participates in social movement.
In this context, 'общественном' describes 'транспорте' (transport), indicating that it is for public use or shared by the community.
В общественном транспорте иногда бывает слишком многолюдно.
In public transport, it is sometimes too crowded.
Here, 'общественном' modifies 'благополучии' (welfare), emphasizing its relation to the collective good or societal well-being.