The phrase per capita is a Latin phrase that means 'for each person.' Per capita measurement makes some comparisons more meaningful than the total for a country. For example, primary energy use becomes primary energy use per capita by taking the total primary energy and dividing it by the population. This allows countries with very different populations to compare energy use meaningfully.
In the interactive graph below, click on the 'per capita' button in order to see how different the order is for total primary energy and primary energy per capita in North America. Also, notice how the units go from millions of tonnes of oil (Mtoe) to tonnes of oil equivalent/per person, quite a difference! This happens because there are millions of people living in each of these countries.