Historically, this entity seems to be added by the original Counter-Strike developers so that Zoner could use it as an "in-map alternative" of the
lights.rad and <mapname>.rad file.
However, this was never implemented in ZHLT (and future forks) and thus this entity is basically useless. The closest equivalent is using
info_texlights instead (or
lights.rad and <mapname>.rad for an "outside of the map" equivalent).