This is the 3717th most frequent Russian word.
успешных
"Successful."
Here 'успешных' is used as an adjective modifying 'людей', denoting their successful nature.
Многие успешных людей делятся своими секретами.
Many successful people share their secrets.
In this sentence, 'успешных' is used as an adjective to describe 'результатов', indicating the success associated with the results.
Для достижения успешных результатов необходима грамотная стратегия.
To achieve successful results, an effective strategy is necessary.
Here 'успешных' is used to describe 'учеников', referring to students who are achieving success.