Log Book service is a service that is completed as per your vehicle's manufacturer's handbook specifications.
A Log Book Service can include:
Oil change, oil filter change, water drained from fuel filter, brake pad thickness checked, exhaust checked for leaks, check fittings are secure and without damage, visual checks of the engine and it's components, condition and tension of belts, coolant levels and anti-freeze protection checked, brake system visually checked for leaks or damage, headlight setting checked, dust and pollen filter replaced, gearbox; final drive and C.V joints checked for leaks and damage, battery checked, tyre tread depth checked, tyre pressure checked, front and rear lighting checked for damage, warning lights and horn checked for operation, operation and adjustment of windscreen wipers...etc etc.
These items could be included in any or all of the service intervals for your car. It depends on the type of car, the type of service and other varying factors. To check what's included in your vehicle's log book service check your vehicle manufacturer's handbook (usually located in your glove box...unless you've moved it).