This is the 17663rd most frequent Russian word.
уверенное
Confident.
The word 'уверенное' is used as an adjective describing 'поведение' (behavior) to denote confidence and assurance.
У него уверенное поведение, которое внушает уважение.
He has confident behavior that inspires respect.
Here, 'уверенное' is an adjective describing 'выступление' (presentation), highlighting her confidence while presenting.
Её уверенное выступление на конференции впечатлило всех.
Her confident presentation at the conference impressed everyone.
In this sentence, 'уверенное' modifies 'решение' (solution), implying certainty and self-assurance in his approach.