what is revealed about justines character in these chapters

I think she is kind and cares about the family she serves. She is also unequipped to defend herself.

Justine confesses to the crime, believing that it will grant salvation, even though she tells Elizabeth and Victor that she is innocent—and miserable. They remain convinced of her innocence, but Justine is soon executed.

We see that Justine is passive and therefore weak (like all women seem to be portrayed), and that although Elizabeth stands up for Justine’s innocence, she, like Justine, is completely helpless to stop the execution.