What is the ruling on a poor person secretly taking money from his friend, the shop owner, knowing that he helps him a lot and is too shy to ask him for money, and what is the ruling on the money he took previously?

If there was no contract or custom indicating that the person performing this work is entitled to a wage, then he is not entitled to demand payment in the first place. He is considered a volunteer in his work. Consequently, his taking money without the owner's knowledge is considered theft, and he must return it. However, if there was a contract or custom stipulating a wage, then he is entitled to demand it.