This is the 3564th most frequent Russian word.
серьезный
Serious.
In this sentence, 'серьезный' means 'serious,' depicting a grave or earnest demeanor of the person.
Он совершенно серьезный человек.
He is an absolutely serious person.
Here, 'серьезный' describes the problem as significant and requiring urgent attention.
У нас есть серьезная проблема, которую нужно решить.
We have a serious problem that needs to be solved.
The word 'серьезное' in this sentence expresses the intensity or substantial effect the movie has.