"The girls have several books."
Translation:De meisjes hebben verscheidene boeken.
I don't think "de meisjes hun" is technically correct grammar, but a lot of native Dutch speakers use that construction for possessive forms. For example:
De klant = The customer
De klants wensen = The customer's wishes
In this situation some Dutch speakers would say:
De klant zijn wensen = The customer's wishes (literally: The customer his wishes)
This stems from the (incorrect) belief that the S at the end of a possessive word is a contraction of "zijn" (his). Sometimes the same construction is used with "haar" for female words and "hun" for plural words. So "de meisjes hun boeken" (the girls their books) means "the girls' books", although it's not correct grammar. "De meisjes boeken" would technically be a correct translation of "the girls' books", but "de boeken van de meisjes" is more commonly used.