This is the 1843rd most frequent Russian word.
объяснила
"Explained" (feminine, past tense).
In this sentence, 'объяснила' is the past tense of the verb 'объяснить', used in the third person singular form, indicating the subject (она) has explained something to the indirect object (мне).
Она объяснила мне, как решить эту задачу.
She explained to me how to solve this problem.
Here, 'объяснила' conveys the act of explaining by the teacher (Учительница), who is the subject, to the direct object (rules) and indirect object (children).
Учительница объяснила правила новой игры всем детям.
The teacher explained the rules of the new game to all the children.
In this example, 'объяснила' signifies the description given by the patient (Пациентка), focusing on the past action of explaining the symptoms to the doctor.