If one body is positively charged and another is negatively charged what will free electrons do?

Generally it flows providing they are touching (or close enough to jump) and are conductors. Please read:
http://www.kpsec.freeuk.com/electron.htm

When one body is positively charged and another is negatively charged, the free electrons in the conductive material will tend to move. Free electrons are negatively charged particles that are able to move within conductive materials such as metals.

In this situation, the positively charged body attracts the free electrons from the negatively charged body. This movement of electrons is what we call an electric current.

To better understand how this happens, let's take a closer look at the concept of conductivity. Conductivity is a property of materials that determines how easily electric charges can move through them. Metals, such as copper and aluminum, are good conductors because they have lots of free electrons that can move around.

When the positively charged body and the negatively charged body are in close proximity or are touching, these free electrons will be attracted to the positively charged body. They will flow from the negatively charged body towards the positively charged body. This flow of electrons is what we observe as electric current.

If you want to learn more about electrons, electric charge, and conductivity, I recommend checking out the link you provided: http://www.kpsec.freeuk.com/electron.htm. It provides a detailed explanation of electrons and their behavior in different materials.