The term actually refers to colleges offering a degree in a course of study comprising the arts and humanities, natural sciences, and social sciences (which may not have direct vocational relevance).
The social sciences generally relate to the study of human experience, society, and social behavior. They include psychology, sociology, anthropology, history, political science, and economics (fields of study are sometimes called disciplines).
The humanities are generally the subjects that relate to humans as intellectual and creative beings. These typically include literature, languages (English as well as all others), philosophy, and the arts, such as fine arts, music, and dance, as well as the histories of these subjects.
The sciences comprise a course of study of the physical or material world, explored through a rigorous and systematic process. They include biology, physics, chemistry, mathematics, engineering, and computer science.
Some courses or majors cross over several of these categories and are called interdisciplinary; they might include social psychology, for example, which crosses sociological issues with those of psychology.
The advantage of a liberal arts education is that you develop a range of skills that will serve you well for the rest of your life. Some courses focus on reading and writing, others expose you to different methods of doing research to prove points, and each subject area requires different analytical and critical thinking skills. Altogether, they help shape a person capable of growing into leadership roles and creatively meeting challenges.