LED substrate of the present invention includes: translucent substrate body-in which an LED chip is disposed on a front face; and heat dissipation path provided in substrate body to dissipate heat generated in the LED chip. The language learning system typically includes a set of fictional characters, each character being associated with a predetermined phoneme of a language, such as English. The supporting unit has a top surface and an outer lateral surface, the top surface is above the light-exiting face, the lateral surface protrudes from an end surface of the lateral side of the plate body, wherein a portion of the end surface away from the light-exiting face is exposed to form a recess.