These are Roman coins.
These particular series of coins are fascinating examples of Propoganda. The reverse (back) shows a giant Roman spearing a small enemy. The Roman is larger to indicate that he is more important and stronger than the (smaller) enemy, Egyptians used this same visual device when depicting the Pharoh and regular people in their art.
The lengend on the reverse reads "Fel Temp Reparatio," which loosely translates as "good times are coming." Pretty intense message to inscribe around a picture of a violent killing.
