The highland climate is pretty simple. It is the climate found around high land. High land means mountains. Mountains can have a completely different climate at the bottom compared to the top. Highland climate is often called Alpine Climate. Nearly every part of this climate--temperature, precipitation, etc. depends on the elevation level.
Highland climate is the climate of 'high' 'land'. So, this climate is found in high mountain areas. It is found on single mountains such as Mount Kilimanjaro and also large areas of high elevation such as the Plateau of Tibet.