I guess Sunil's ISP (could be Beam tele) provides a switch for whole building with fiber optic cable and from the switch he gets an ethernet cable (with RJ45 connector). Its a pure cable connection and you cannot connect it to an ADSL modem. You can rather connect it directly to a Router (buy a cheaper NRouter for some 1000 bucks) and configure it. If ISP gave you log in details you have to configure your router in PPPoE to avoid logging in every time you open a web page.
As an update, ADSL is only for telephone connections (like BSNL, Airtel etc in India) which needs a splitter that separates phone line and internet line.