Deciding whether to call someone a "girl" can be tricky. Here are a few guidelines:

• You usually don't call someone a "girl" if they are more than about 5 years older than you.
• A person who's old enough to be a grandmother isn't usually called a "girl".
• It's more appropriate to call a friend or someone you know socially a "girl". Calling someone you know through business a "girl" is usually not a good idea.
• Men should be more careful about calling someone a "girl" because it can seem condescending.

In the example above, the speaker is female and talking about another woman who's around the same age, so she says "girl".