Here's a breakdown:
* sabon - soap
* buhok - hair
* panligo - for bathing
So, literally, "sabon sa buhok" means "soap for hair" and "sabong panligo sa buhok" means "bathing soap for hair".
However, the more commonly used and understood term is simply shampoo. This is because the English word has become widely adopted into the Tagalog language, just like many other English words.