In medieval times, a franklin was a free landowner who was not a man of noble birth. As a free man, a franklin did not owe rent or military service to the monarchy.
Franklins were born as free men; they did not gain their freedom by purchasing their lands from the Crown. They were often wealthier than the peasants but not as wealthy as the lords who ruled the area as proxies for the king.
"The Franklin's Tale" is famously known as one of Chaucer's Canterbury Tales. In that story, the Franklin demonstrated his wealth by opening his home to the inhabitants of the surrounding countryside.