The term 'Century Units' refers to two different units of measurement: LEGIONS and years. A legion is a unit of measurement used in the Roman Empire, typically referring to a military unit of around 5, 000 soldiers. Years, on the other hand, are a unit of time measurement, typically referring to a period of 365 days. Both of these units are commonly used to measure the passage of time, with a century being equal to 100 years or 10 LEGIONS.