A palette is a limited index of colors defined as a subset of the total range of displayable colors. Any given game will generally contain many such palettes.
The SNES uses a 15-bit format to describe a single color entry. 5 bits are allocated to each of the three red, green, and blue color components. Therefore, a single color is stored in two bytes, as such:
Note that colors are stored in little-endian format, exactly as shown. In other words, when read as a 16-bit byte, the most significant bit of the least significant byte is 0.