In that sense, even though there is only one light, we refer to the lights in the Sefirot [in plural] as “NaRaNḤaY,” for the light changes depending on the qualities of the vessels. Malkhut is the thickest cover that shields the light of Ein Sof, such that only a small measure of light passes through to recipients. This is appropriate to the purity of the inanimate aspect of the human body, which is why it is referred to as Nefesh.
The vessel of Tiferet is purer than that of Malkhut. Hence, the light that passes through it from the Ein Sof is linked to the purity of the plant aspect in the body of man, which is more active than the light of the Nefesh and is called the light of Ruaḥ. The vessel of Bina is even purer than that of Tiferet, and therefore the light that passes through it from the Ein Sof is linked to the purity of the animal part of the human body, which performs great actions and is called the light of the Neshama.
The vessel of Ḥokhma is the purest of all. The light that passes through it from the Ein Sof is linked to the purity of the human aspect of the body of man, and it is called the light of Ḥaya, which has infinite actions, as will be explained.