There are two types of flying hours to consider, total hours and hours on type:

Total Hours.
This relates to the total hours a named pilot has logged on this category of aircraft (e.g. helicopter, aeroplane etc.) Note that unpowered glider hours are not to be included when calculating total aeroplane hours but powered glider and microlight hours may be included.

Hours On Type
This relates to the total hours a named pilot has logged on this make and model type (e.g. Piper PA28 is a make and model type, Cessna 150 is a different make and model type etc). Note that hours spent on variants of a model type can be included (e.g. Piper PA28 is a model type and would include hours on a PA28 140, PA28 160 etc).