The '80' indicates 80 signal positions (plus 4 power pins), 'P' denotes a header connector type, and '0.5SV' refers to a 0.5mm pitch, straight, vertical connection. The '15' specifies a mated stacking height of 15mm. The FX23 identifies the series of Hirose Electric's high-speed transmission, 0.5mm pitch board-to-board floating connectors.