This is the 8349th most frequent Russian word.
многим
"Многим" means "to many" or "for many" in English.
Refers to 'many people' (dat. plural), the indirect object of 'нравится'.
Многим нравится этот фильм.
Many people like this movie.
Indicates 'to many of us' (dat. plural), specifying a subset of a group.
Многим из нас нужно было участвовать в проекте.
Many of us needed to participate in the project.
Identifies 'many people' (dat. plural), receivers of the help.