He might be referring to the "hydraulic analogy" of electricity: A wire is a water pipe, voltage is water pressure, amperage is total water flow. A battery is a pump pushing water through the pipes, voltage is how hard the pump pushes, and amperage is limited by how wide the pipes are, and thus how much resistance they impose on the flow of water.

http://en.wikipedia.org/wiki/Hydraulic_analogy

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/watcir.h...