It means "I really don't like it", "I'm not interested in it", it's rather formal. It can also mean (for math or verlan for example) that you don't understand it, you're not good at it. (Usually if you don't like math it's because you find it hard).
Sometimes, it carries the idea that you don't respect it very much, or that you're being sarcastically polite. WordReference has "Thanks but no thanks" as one of the translations.
You can see it that way : you're at a dinner, the host serves a dish to all the guests, but you really don't like it, so when it's your turn you say "Très peu pour moi", which means roughly "Give me very little, please". You're being offered something but you really don't like it. You'll still have some because you're polite and it would be rude to refuse, but you're asking for as little of it as possible.