The word flux comes from the Latin to flow. What does the quantity ΦE = E¥ A

The word flux comes from the Latin "to flow." What does the quantity ΦE = EŠ¥ A have to do with flow? The figure shows some streamlines for the flow of water in a pipe. The streamlines are actually field lines for the velocity field. What is the physical significance of the quantity vŠ¥ A? Sometimes physicists call positive charges sources of the electric field and negative charges sinks. Why?