This is the 98th most frequent Russian word.
начала
The Russian word "начала" can mean "began" (past tense of "begin") or "principles" depending on context.
In this sentence, 'начала' is the past tense singular feminine form of the verb 'начать', meaning 'to start', and it describes the action of starting something.
Она начала работать здесь год назад.
She started working here a year ago.
Here, 'сначала' is an adverb meaning 'first' or 'at first'. It indicates the sequence of actions.
Сначала мы приготовим обед, а потом пойдем гулять.
First, we will cook lunch, and then we will go for a walk.
In this context, 'начала' is a noun in the plural form, meaning 'foundations' or 'principles'. It refers to the core concepts.