In the first place, hermenuetica means expression of a thought, but Plato has expanded the sigificate to the explanation or interpretation of a thought. Then the term was also used to refer to the art of interpreting the Holy Scriptures. But hermeneutics has acquired peculiar relevance to the history of philosophy from the contributions of Dilthey.
Hermeneutics is an interpretation based on a previous knowledge of the data (historical, philosophical) of reality that is trying to understand, but at the same time gives meaning to the data through an inevitably circular process, very typical of understanding as a peculiar method of the sciences of the spirit. Thus, hermenuetics facilitates the work by giving tools to understand an author better than his contemporaries could.
Hermeneutics is based on historical consciousness, the only one that can reach the wondo of life: it passes from the signs to the original experiences that gave birth to them, is a general method of interpretation of the spirit in all its forms and therefore constitutes a science of greater scope than piscology (which, on the other hand, for Dilthey is just a particular form of hermeneutics.
Dilthey, a method for the sciences of the spirit