Ceramic capacitor with a capacitance value of 100pF, voltage rating of 1200V or 1.2kV, and a tolerance of ±1%. It is designated as CER 100PF 1.2KV C0G/NP0 1210. The part number indicates it's a 1210 (3225 Metric) size capacitor with a C0G or NP0 dielectric type.