A nice girl is a woman who is pleasant, friendly, and accommodating to others. The antonym of 'nice girl' is nice guy.
Nice girls are sometimes mocked in the same way that, "nice guys", are. For example, some nice girls are labeled as suffering from, "nice girl syndrome". The insult being that nice girls sometimes feign niceness or expect too much from society for their good personality.
Nice girls and inceldom
It is unknown whether being a, "nice girl", is a hindrance in dating, but the topic of niceness causing dating issues is common in the incelosphere.