hard sai kal

Not sure but I'm thinking of a carabao song that says had sai kao, meaning "white sand" - probably not what you are trying to say.

หาด hàat - beach

ทราย saai - sand

haad saai khaaw หาด ทราย ขาว means White Sand Beach - there is one beach so named on many Thai islands, perhaps the most well-known one is the Haad Saai Khaaw on Koh Chang.

"kal" with an 'l' sound at the end is not a possible pronounciation in Thai - so I assume you mean a 'w' sound at the end.

It could also be you use 'a' to represent the vowel แ as well. In that case, the last word could also be 'kaew[F]' แก้ว - glass; emerald. If so, the beach would be Emerald Sand Beach.

But the first alternative White Sand Beach is more likely.

Need to see it in a sentence to be sure, but K. Neeranam's and K. Meadish Sweetball's explanations are very likely. Is it a noun, verb, complete sentence etc???

I think it's a Nga Caravan's song, btw. There's a song called "Kor Hard Sai Kao Hai Tao Ma Fueng" (Give the White Sand Beach to the Mafueng turtles).