This is the 14016th most frequent Russian word.
овладеть
"To master" or "to seize."
The word "овладела" here refers to successfully learning and understanding the use of a tool or system.
Она быстро овладела новой программой.
She quickly learned to operate the new software.
The word "овладел" here means to have gained a high level of skill or knowledge in a specific field or activity.
Он овладел искусством фотографии.
He mastered the art of photography.
In this sentence, "овладеть" means to familiarize oneself with or gain an understanding of necessary fundamental concepts.