They're a way to describe how a coffee tastes, according to terms common in the specialty coffee industry. These descriptions can help you determine what characteristics you like and what coffees you might like to try.
Coffee is all a matter of taste preference.
And your preferences may vary depending on your mood, the day, or even the time of day. You can find excellent coffees that fall along any part of these ratings scales. It's a good thing. It contributes greatly to the liveliness, zest, or snap of a cup of coffee. By the way, there's no more acid in a cup of coffee than there is in a can of cola or a glass of apple juice.