Cats meow to get attention from their owners. They may meow when they want to be fed, played with, or petted.
Cats also meow to communicate with other cats. They may meow to greet each other, to ask for help, or to show dominance.
If your cat is bored, they may meow to get your attention or to try to find something to do.
If your cat is in pain, they may meow to let you know. This is especially true if they are injured or sick.
In some cases, excessive meowing can be a sign of a medical condition, such as hyperthyroidism or cognitive dysfunction syndrome.
If your cat has recently experienced a change in their environment, such as moving to a new home or the arrival of a new pet, they may meow more than usual.
Some cats are simply more talkative than others. If your cat is a natural-born chatterbox, then you may just have to get used to their constant meowing.