Kenneth Wright, in Mirroring and Attunement, describes her approach:
For Langer, then, the work of art is a complex symbolic rendering of emotional life in a form that enables apprehension of its being rather than comprehension of its meaning. Its non-verbal symbols articulate the shapes and textures of living experience rather than its cognitive definition, and because they present this semblance in analogical form, she called them presentational symbols. Art does not, in the manner of language, describe experience but offers it directly to our senses through iconic forms. It is not an alternative means of expressing emotion but a means of revealing its forms in a concrete, yet quasi-abstracted way.
I have to admit my fondness for this definition, if only because it resonates with my very first thought on this blog.