As you just learned, a claim is supported by reasons, which are supported by evidence. Evidence can include facts, statistics, examples, expert opinions, definitions, or anecdotes. Identifying evidence can help you determine how well the author supported his or her reasons.
Take a look at this statement:
Eating blueberries frequently is important because they’re good for you. They are low in calories and contain more antioxidants than other kinds of fruit.
The claim — that eating blueberries frequently is important — is supported by the reason, that they’re good for you. This reason is supported by two facts — they’re low in calories and they contain antioxidants.