This is the 323rd most frequent Czech word.
začala
"Začala" means "started" or "began" (feminine singular, past tense).
The word 'začala' conveys the start of the action, specifically the commencement of the lesson by the teacher.
Učitelka začala hodinu.
The teacher began the lesson.
Here, 'začala' indicates the initiation of a natural growth process as a result of rain.
Po dešti začala tráva růst rychleji.
After the rain, the grass began to grow faster.
In this sentence, 'začala' expresses the onset of the action of learning by Marie.