This is the 2869th most frequent Russian word.
бесплатным
"Бесплатным" means "free" (without cost) in English.
Here, 'бесплатным' is used as a predicate adjective in instrumental case, agreeing with the noun 'мероприятие', to express that the event is provided without cost.
Это мероприятие является бесплатным для всех участников.
This event is free of charge for all participants.
In this sentence, 'бесплатным' is an attribute describing the noun 'билет' in instrumental case after the verb of perception, signifying that there was no charge for the ticket.
Билет оказался бесплатным, к моему удивлению.
The ticket turned out to be free, to my surprise.
The word 'бесплатным' serves as a predicative adjective, referring to the noun 'сервис' and indicating a transition to a no-cost state starting this month.