Islam does not enforce restrictions on dancing and singing because they are negative in and of themselves. Instead, Islam enforces restrictions to protect men and women from breaches in modesty and dignity. Although there are still a degree of modesty that both genders need to exercise around members of their own gender, the Quran states that women can reveal their beauty amongst other women. Therefore, as long as the dancing and singing are not of some intrinsically haraam nature (for example, songs with haraam lyrics), it is not haraam to enjoy these activities with other women. There is difference of opinion on this topic though and Allah knows best ultimately.