You have to view and understand first the two words and how in sociology positivism is being considered. In sociology, positivism is the view that social phenomena (such as human social behavior and how societies are structured) ought to be studied using only the methods of the natural sciences. So, positivism is a view about the appropriate methodology of social science, emphasizing empirical observation. It is also associated with empiricism (the view that knowledge is primarily based on experience via the five senses), and it is opposed to metaphysics roughly, the philosophical study of what is real on the grounds that metaphysical claims cannot be verified by sense experience.
Therefore, positivism is a way of thinking developed by Auguste Comte and is based on the assumption that it is possible to observe social life and establish reliable, valid knowledge about how it works. This knowledge can then be used to affect the course of social change and improve the human condition. Positivism also argues that sociology should concern itself only with what can be observed with the senses and that theories of social life should be built in a rigid, linear, and methodical way on a base of verifiable fact. It has had relatively little influence on contemporary sociology, however, because it is argued that it encourages a misleading emphasis on superficial facts without any attention to underlying mechanisms that cannot be observed.
According to Talcott Parsons viewed society as a system. He argued that any social system has four basic functional prerequisites: adaptation, goal attainment, integration and pattern maintenance. These can be seen as problems that society must solve if it is to survive. The function of any part of the social system is understood as its contribution to meeting the functional prerequisites.
With that guideline you can continue