Animal abuse is when an animal is exposed to domestic violence, keeping an animal in unsafe conditions, or even killing them. It could even be your actions or lack of action too.
Here are some more examples:
Animals being euthanized in shelters
Dogs being kept in puppy mills
Wild animals being kept in unhealthy captivity conditions
Wild animals being hunted
Animals in the food chain being kept in filthy, inhumane conditions
etc.
This website would talk about the types of animal abuse and how you can help animals. Each subtopic is a different form of abuse.
One of the best ways for helping these animals is by going vegan, if you are up to it. You can also donate to conservation societies that are well trusted.