The abbreviation "pm" generally stands for "post meridiem" in Latin, which translates to "after noon." It is used to indicate the time of day from 12:00 noon until 11:59 at night in the 12-hour clock system. For example, if it is 3:00 pm, it means three hours after noon.
"pm" comes from the Latin phrase "post meridiem," where "post" means "after" and "meridiem" means "midday" or "noon."