“To do justly” is too act with equity, fairness and deference to those who are in a weaker social position—the opposite of the violence, oppression, fraud, lying and injustice.
Justice is the Hebrew word mishpat, and it can convey one of 2 separate meanings….
The first is retributive. You have to pay the consequences for what you do wrong. “Do the crime, you must do the time.”
But most often in the Bible “mishpat” refers to restorative justice. It means to go a step beyond just administering punishment. It means seeking out those being taken advantage of and helping them. More than just charity, it means to advocate for the oppressed.