what does salao mean?

Salao comes from the Spanish word salado, meaning salty. Salao is used in the context of a fisherman being unlucky. This refers to Santiago not catching any fish and Manolin's parents refusing to let Manolin fish with the old man.

The Old Man and the Sea tells the story of a battle between an aging, experienced fisherman, Santiago, and a large marlin. The story opens with Santiago having gone 84 days without catching a fish, and now being seen as "salao," the worst form of unluckiness. He is so unlucky that his young apprentice, Manolin, has been forbidden by his parents to sail with him and has been told instead to fish with successful fishermen.

So " Salao" means the worst form of unluckiness.

In The Old Man and the Sea, we get the word "Salao". Basically it is extracted from the Spanish word " Salado" which manifests "salty"__ Truly speaking this word is bestowed upon the protagonist, Santiago for his unlucky streak. For his hapless conditions, the local fishermen calls him by saying that ominous word.