Is it permissible to give votive money to a friend who is about to get married and needs the money, and is that considered a form of charity, and is it obligatory to inform him of the true nature of this money or can it be considered a gift, and is it permissible to give this money from zakat?

There is no objection to giving the vowed charity to a friend to help him with his marriage expenses, without informing him of the nature of the money. It is permissible to give him from Zakat (definition) for his marriage needs, provided there is no extravagance or wastefulness. It is not permissible to give one sum of money for both a vow and Zakat.