Himalayas act as a climatic barrier and prevents the cold north east monsoon from Russia.If Himalayas were absent India would have been that very cold.
Himalayas obstructs the monsoon wind and makes rain to fall on the sub continent.If not India would have been a hot dry desert.
It acts as a tourist spot attracting many tourists all around the world.
Himalayas act as a major source of perennial rivers like Ganga,Bhramaputra,godhavari,etc
Himalayas acts as a huge source of minerals and hydro electric power plants.