Either a faulty mass air flow sensor or faulty air intake sensor.
Usually, these sensors are located on the air fiter hose leading o the intake.
It depends on what year your civic since some have air intake and some have mass air flow sensors.
Basically, what it means is the computer (sensor) is not reading the proper flow rates for your vehicle. This affects the car in ways such as irregular idle speed, lower gas mileage, and poor accelaration.
My suggestion is to take it to any parts store, Autozone, Napa, etc and they will, based on your engine and year of car be able to assist you with replacing that part.
Hope I helped@!