This is the 11448th most frequent Russian word.
довольной
The Russian word "довольной" means "satisfied" or "content" in English.
Here, 'довольной' is used as a predicate adjective in the instrumental case, agreeing with 'она' and indicating a state of satisfaction.
Она осталась довольной результатами работы.
She was satisfied with the results of the work.
In this sentence, 'довольной' also functions as an adjectival form in the instrumental case, describing the appearance or state of 'её' (her).
Я никогда не видела её такой довольной.
I have never seen her so content.
Here, 'довольной' is part of a description in the instrumental case, complementing 'себя' to express her satisfaction or contentment with life.