Complex sentence: In epidemiology, the prevalence or prevalence proportion is the proportion of people in a population who have a condition (typically a disease or a risk factor such as smoking or seat-belt use) at a specific time, usually the time of the study.
Split into simpler sentences: In epidemiology, the prevalence or prevalence proportion is the proportion of people in a population who have a condition (typically a disease or a risk factor such as smoking or seat-belt use). "Point prevalence", often simply "prevalence", is the proportion of a population that has the condition at a specific time, usually the time of the study.