What does the allusion "this here can is empty as jacob's kettle" mean?

This is from "A Raisin in the Sun" written by Lorraine Hansbury. Hansbury is referring to the biblical story of a woman who went get water. The woman's kettle was empty and Jesus told the woman that if she had faith, she would be would have living waterwas going to get some water. Her pot (or kettle) was empty. Jesus tells her that if she believes, then she will have living water and her spiritual life/well would never run dry like a kettle or well filled with water used to sustain physical life. Basically, an empty kettle could be filled through faith/belief.