Something prevalent is common in a particular place at a particular time. Prevalent things are hard to avoid. When you see the word prevalent, think "It's everywhere!"
Have you ever noticed how all of a sudden a new word, band, or hairstyle will become super-popular? You may never have seen those things before, and then suddenly they're prevalent. When something is common, it's prevalent. You could say drug use is prevalent among criminals. You could say good study habits are prevalent among good students. If a certain opinion is common, then that's a prevalent view in society.