Something that's galling is frustrating or exasperating. A galling argument with your parents leaves you irritated and indignant.
Galling things make you angry. It would be galling to lose your job because of someone else's mistake, and it's galling to see some members of society being treated unfairly and feeling helpless to do anything about it. An article with a galling viewpoint makes you fume. Galling comes from the verb gall, which means "annoy," but originally was "chafe or rub until sore."