We talk to tell someone we want them to pass the salt. We talk to ask questions, share feelings, and ask for directions when we are lost. We talk to ourselves in our thoughts, and we speak out loud.
In our stories, our characters talk, too. It is not quite as easy to write dialogue for our characters as it is to have conversations in real life. But if you take time to learn how dialogue works and practice writing it, you will be able to write brilliant conversations that sound natural and move your story forward.