This is the 3494th most frequent Russian word.
развитых
"Развитых" means "developed" in English.
In this sentence, 'развитых' is used as an adjective meaning 'developed', describing 'countries', showing possession of advanced development.
Многие развитых стран активно внедряют новые технологии.
Many developed countries actively implement new technologies.
'Развитых' here is used as an adjective describing 'students', meaning 'advanced students' who have reached a higher developmental level in their studies.
В программу обучения включены курсы для развитых учащихся.
The educational program includes courses for advanced students.
In this instance, 'развитых' refers to 'intellectuals' who are well-developed or advanced in their intellectual capabilities.