Fixable things in this instance could include items that are mechanised such as stamps, pipes, crooked furniture, flashlights, circuitry and even cars.
Improvised devices being things like makeshift items being put together with a series of nearby found objects due to an current lack of proper peripherals like door handles, things to hold doors open, microphone stands made from masking taping things together like tables and crates, think McGyver style combinations.
I know a guy that can do this kind of thing without a second thought and it just leaves everyone else nearby a bit gobsmacked. He was with me last week at a campus music night and he just sort of calmly solved all these logistical problems and fuckups that everyone else was just scratching their heads at. I'm decent at this kind of thing, but not quite as fast or confident at it as this guy.