Questions & Answers about Она сказала, что я не виноват, и мне стало легче.
Because the subject is она. In the Russian past tense, verbs agree with the subject in gender and number:
- он сказал = he said
- она сказала = she said
- оно сказало = it said
- они сказали = they said
So сказала tells you the speaker is talking about a female person.
Сказала comes from сказать, which is usually perfective. It presents the action as a single completed act: she said it, and that moment is treated as finished.
Говорила comes from говорить, which is imperfective. It usually means something more like:
- she was speaking
- she used to say
- she was telling
In this sentence, the point is that she said one specific thing, so сказала is the natural choice.
Here что means that and introduces the content of what she said:
- Она сказала, что... = She said that...
In English, that is often optional: She said I wasn’t to blame. In Russian, что is normally kept in this kind of sentence.