One-liner
Two versions of the same fund: a distribution class pays income into your account on a schedule; an accumulation class reinvests it automatically and grows the price instead.
Why it matters
If you need income, distribution is the clean choice. With accumulation you would have to the cash yourself, which adds cost and the risk that idle money just sits there because you forgot to redeploy it.
Analogy
It is like a herd with a new calf. Sell the calf and you get cash to do something else, but the herd stops growing. Keep it and the herd compounds, just do not expect milk money this month.
The catch
Buying a fixed-income fund for predictable income and picking the wrong class can cost you: you end up redeeming at a bad moment and paying costs you would have avoided with the class that actually fit your need.