Meaning: The farmer wanted to make sure the baby pigs were well.
Choice of Words: A "farmer" is a person who works on a farm. "Checked" means to examine something to make sure it is in good condition. "Piglets" are baby pigs. "Health" is the state of being physically and mentally well. So, "Farmer checked the piglets' health" means that the farmer examined the baby pigs to make sure they were healthy.