This final paper deals with the issue of how we acquire and produce language. The focus is placed on speech errors and their nature of providing evidence for the processes that lie behind language acquisition and production. To begin with, in the first chapter of this work, the description of how we learn a language step by step is provided following the child’s development of speech comprehension and production; from the so-called vegetative sounds, such as crying, to proper words with a meaning attached to them. The second chapter of this paper deals with language production, with attention paid to the presumed model of speech production, where every stage of the model is elaborated and explained. Eventually, in the third chapter, we discuss speech errors. There are three major sections within this chapter: the types of speech errors, where several basic types of speech errors are enlisted and explained, followed by observation of their properties, and finally, all of that led us to evidence that speech errors provide for the processes of speech production.