What does Rudolf Steiner's Philosophy Of Freedom mean by intuition? A common dictionary definition calls intuition a feeling:

“an ability to know or understand something through your feelings, instead of by considering facts or evidence.”

The best I can tell, for the Philosophy Of Freedom, intuition means the appearance of thought in your mind, specifically concepts and ideas. It is becoming aware of or perceiving pure concepts and ideas. At least this is the important aspect of intuition to Steiner's basic philosophy. Intuition is explained in Chapter 5. By thought it means in this case “concepts and ideas”, so I added this in parentheses to the quote:

Thought contributes this content to the percept from the world of concepts and ideas. In contrast with the content of perception which is given to us from without, the content of thought (concepts and ideas) appears within our minds. The form in which thought (concepts and ideas) first appears in consciousness we will call "Intuition." Intuition is to thoughts (concepts and ideas) what observation is to percepts. Intuition (the faculty of perceiving concepts and ideas) and observation are the sources of our knowledge. An external object which we observe remains unintelligible to us, until the corresponding intuition (concepts and ideas) arises within us which adds to the reality those sides of it which are lacking in the percept. To anyone who is incapable of supplying the relevant intuitions (concepts and ideas), the full nature of the real remains a sealed book. Just as the colour-blind person sees only differences of brightness without any colour qualities, so the mind which lacks intuition (the faculty of perceiving concepts and ideas) sees only disconnected fragments of percepts. POF 5-10

What is a pure concept that intuition perceives?

With pure concepts and ideas the content is contained within the thought-form itself. By concept is meant a principle according to which the disconnected elements of perception become joined into a unity.

Causality, for example, is a concept. An idea is a concept with a greater content. Organism, considered quite abstractly, is an idea. However, they must be considered in the form which they possess while still quite free of any empirical content. If, for example, the pure idea of causality is to be grasped, then one must not choose a particular instance of causality or the sum total of all causality; it is essential to take hold of the pure concept, Causality. Truth and Knowledge iv The Starting Point Of Epistemology

Later, in theosophy-anthroposophy, Steiner speaks of concepts as beings, spiritual or etheric formative forces, which drive the world from within and which lie at its foundations. This definition of concept involves the development of higher faculties of perception of the spiritual world that still remains highly speculative for science and unreachable for most who lack Steiner's claimed clairvoyant abilities so it is not included in The Philosophy Of Freedom.