This is the 13172nd most frequent Russian word.
мечтающих
"Dreaming" (present participle of "мечтать").
The word 'мечтающих' functions as a present participle describing people who are currently dreaming or aspiring for success.
Мечтающих достичь успеха всегда много.
There are always many who dream of achieving success.
In this case, 'мечтающих' is used to describe individuals in general who aspire for improvements in their lives.
Она всегда поддерживала мечтающих о лучшей жизни.
She always supported those dreaming of a better life.
Here, 'мечтающих' specifies people who currently have the ambition or dream of becoming artists.