According to Wikipedia, "Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries between the natural and social sciences. Psychologists seek an understanding of the emergent properties of brains, linking the discipline to neuroscience. As social scientists, psychologists aim to understand the behavior of individuals and groups. Ψ (or psi) is a Greek letter which is commonly associated with the science of psychology."
Psychology is about our mind, thinking, and behaviour. Psychology helps you understand yourself and other people, and helps to maintain good mental health.
Wikiversity is a Wikimedia Foundation project devoted to learning resources, learning projects, and research for use in all levels, types, and styles of education from pre-school to university, including professional training and informal learning.
There are lots of self-learning contents about psychology, which you can study by yourself before going into a formal education.
There are some interesting topics that you may have a look: