With the significance of the wine shop owned by the Defarges well established in Chapter V of Book the First of A Tale of Two Cities, the gathering of the men known anonymously as "Jacques" represents the emerging "hundreds of footsteps" that will soon march upon the Bastille, the symbol of political oppression.
That there is an aura of subterfuge and suspicion in the wine-shop is evinced by the actions of Madame Defarge who coughs and raises her eyebrows significantly; also, after looking at some of those who enter the shop, she takes up her knitting "with great apparent calmness and respose of spirit" and becomes totally absorbed in it.
Further, outside, the three Jacques peer with great interest into the room where Dr. Manette is confined. Ernest Defarge explains to Mr. Lorry that he shows Manette to a chosen few. When Mr. Lorry asks which few, Defarge replies,
"I choose them as real men, of my name--Jacques is my name--to whom the sight is likely to do good."
Because Manette has been imprisoned in the Bastille by the aristocrats Evremonde, Defarge's remark about the Jacques also indicates that the revolutionary movement is in its incipience (i.e., beginning).
The name is a veiled reference to the Jacquerie, a rebellion by French peasants during the Hundred Years War. The name was a pejorative term applied to the peasants by the lords against whom they revolted. Thereafter, Jacques was a name peasants used to identify themselves as members of the revolutionary movement. The term was often used to describe a peasant uprising.
It's a code name for the rebels involved in the revolution. A source says that among strangers, people would refer to each other as Jaques to identify themselves as revolutionaries.
this is used like a code; it protected for being known to others .if there was a spy of the king there he could not know the original name of the others so u may say also 4 safty they used this