Mr. Heck Tate is speaking for the courtroom on account of Mayella's attack. Scout and Jem are watching the entire court case.
After Heck's testimony, Mayella's father makes his testimony. He uses very rude and crude language and insults Atticus. The fact that Mayella tried to pursue Tom Robinson is unheard of. It breaks the rules of Maycomb and starts a new beginning.
Mayella then conducted her testimony and was not very sure with any of her words. Mayella seems to not be able to tell the truth. Maybe she was told not to tell the truth by her father. Maybe he threatened Mayella and said that he would beat her again if she told the truth.