A ceramic capacitor with the part number CAP CER 3900PF 1.2KV X7R 1206 has a capacitance value of 3900 pF and an acceptable tolerance of ±20%. It is rated for high voltage applications at 1200V (1.2kV) and features a metric size of 3216, making it suitable for use in electronic circuits that require precise capacitance values and reliable operation within extreme voltage conditions.