This is the 652nd most frequent Russian word.
подчеркнула
"Подчеркнула" means "emphasized" or "underlined" in English.
'подчеркнула' is used here in its more literal sense, referring to physically marking or underlining something to highlight its importance or presence.
Учитель подчеркнула ошибки в сочинении красной ручкой.
The teacher underlined the mistakes in the essay with a red pen.
Here, 'подчеркнула' is used to imply enhancing or making more noticeable a positive attribute, in this case, beauty.
Её новая причёска только подчеркнула её красоту.
Her new hairstyle only emphasized her beauty.
In this sentence, 'подчеркнула' is used to indicate that someone has stressed or drew attention to a particular point, namely the importance of following rules.