The light that is good
The light was everywhere. This is deemed to be good (טֹ֑וב), that is, pleasant. The state of the light is indicated by the conjunction כִּי, kiy, which is most often translated "that".
The creation of light had been by sound waves over the surface of the water in contact with God. This produced light everywhere at the same time. This wave motion would become the basis for everything to follow.