Qadar القَدَر means fate, or destiny. In Islam we are to have faith in fat/destiny both it's good and bad.
قال : فأخبرني عن الإيمان .
قال : أن تؤمن بالله وملائكته وكتبه ورسله واليوم الاخر وتؤمن بالقدر خيره وشره .
he went on to say, "Inform me about iman (faith)." He (the Messenger of Allah) answered, "It is that you believe in Allah and His angels and His Books and His Messengers and in the Last Day, and in fate (qadar), both in its good and in its evil aspects."