Well, this word is not usually used in normal day-to-day conversations. It means something disturbing or that puts you unease. Example: Ang kanyang nasaksihan ay nakakapagpabagabag sa isipan. (What he just witnessed is mentally disturbing) Hindi ko siya maiintindihan at ito'y nakakapagpabagabag ng aking damdamin (I can't understand her and this makes my feelings unease)