Does anyone know what this approach chart symbol is?
What you want is the Frontmatter to the Terminal Procedures Publication, and in particular the pages under "Approach Lighting System" -- these document all the various permutations of visual approach aids found in the US NAS.

As to the symbols you are specifically asking about -- the "shell" is the standard symbol for an ODALS (OmniDirectional Approach Lighting System) that consists of two steady burning lights at each side of the runway threshold and five sequenced flashers leading down the extended runway centerline for 1500'.  The two circled "P"s are also standard symbols, but for PAPI (Precision Approach Path Indicator) lights -- a set of four bicolor (red/white) lights that sit beside the runway and are aimed so that you can see if you're above, on, or below the glidepath based on the combination of red and white lights you see.

As to the symbols being reverse (not boldened)?  That means that those lights are hooked up to a PCL (Pilot Controlled Lighting) box that listens for sequences of microphone clicks on the airport control frequency (UNICOM/CTAF, or tower for a part-time towered airport) and turns on the lights hooked up to it for a set period of time when a suitable sequence is given by a pilot.