The right to petition government for redress of grievances is the right to make a complaint to, or seek the assistance of, one's government, without fear of punishment or reprisals. The Article 44 of the Charter of Fundamental Rights of the European Union ensures the right to petition to the European Parliament. —— From Wikipedia
Right to Petition the Government for a redress of grievances means that citizens can hand the indictment to the court. Rights of expression is the first step for the citizens to express their opinion and protect their rights. Through the petition, citizens can complaint the actions of government, such as enforcing new laws, deal with the national issues. The petition is also a way for the government to know about citizens' complaint.
So that the picture shows the process of the petition and that all citizens have the right and freedom to complain.