Liberty means the condition in which an individual has the ability to act following his or her own will and alternatively, achieve their potential, within the context of other words like political freedom. It is a term that has contested meanings.
Communism and socialism claim to have something defined as liberty for them because of their social equality ideals. Libertarians and classical liberals think communism is against Liberty because communism is most of the times against the individual basic rights (life, freedom and property).