Squealer is a literate pig, Napoleon's helper who is good at convincing and making excuses. He's always on his side, he tries to convince animals that Napoleon is a good leader. He tried to justify his actions even though Napoleon didn't actually help the farm.

He taught some smarter animals the alphabet. When animals got confused at the tasks that were given to them, Squealer always said something that made them do the work, he tried to ´motivate´ them.

He's good at explaining, he managed to explain why have more food just by giving threats to the animals, like for example if the pigs who call themselves brainworkers didn't get enough mush, their brain will stop working and Mr. Jones will come back to the farm.

His speech is always described as squeaking or crying, that's probably the reason why he has that name. At the same time, squeal means betray, he betrayed the farm to stay loyal to Napoleon and his cruel plans.