Here's a breakdown:
* लघु (laghu) means "short"
* संदेश (sandesh) means "message"
* सेवा (seva) means "service"
So, लघु संदेश सेवा (laghu sandesh seva) literally translates to "short message service".
You can also use the more common term SMS (एसएमएस) which is widely understood in Hindi.