This is the 5256th most frequent Japanese word.
高山
"高山" means "high mountain" or "alpine."
高山 is used here to refer to high-elevation mountains.
日本アルプスには高山が数多く存在しています。
There are many high mountains in the Japanese Alps.
高山 in 高山植物 specifies 'alpine' or 'high-mountain' as the ecological type.
高山植物は厳しい環境で育ちます。
Alpine plants grow in harsh environments.
Here, 高山 is part of a surname, meaning it is used as a proper noun.