For Einstein named concepts are related to sense experiences.* The notion of "dog" (der begriff hund) can correspond (entsprechen) to the many (mannigfaltigkeit) immediate (unmittelbar) experiences that one has while saying (or hearing) the word "dog."** This is exactly how A.s.a. H. learns concepts and the words that denote them.***
*Holton, The Scientific Imagination, Harvard U. Press 1998
**Feinberg, Zwei Kulturin, Springer 1998
***Jones, Trans. Kan. Acad. Sci., vol. 120, page 108, 2017 and chapter 1 of my book Twelve Papers.