The Siemens 5TT5830-6 is a SENTRON insta contactor with four normally-open (NO) contacts and zero NC contacts. It's designed for switching loads up to 400 V and 25 A, controlled by a 230 V AC coil. The 2000 W incandescent lamp switching capacity tells you it can handle tungsten inrush, which is a common test for lighting panels.
The 4 NO contact arrangement is common for switching multiple loads simultaneously, like a bank of lights or a group of small motors. And yes, you can bolt on supplementary devices — the product extension flag is set to yes.