Is it permissible for the husband to give his first wife what he owes her of money, knowing that he also owes his second wife money, and he says that the first wife has priority and he will give the second wife later?

Your husband is either well-off or in straitened circumstances. If he is well-off and your debt is due and you demand it, then he has no right to delay it or to prefer his first wife, for the Prophet, peace and blessings be upon him, said: "The delay of a rich person (in paying his debt) is an injustice." If he is in straitened circumstances, then he must be given respite until he becomes well-off, for Allah Almighty says: "And if there is any debtor in difficulty, then grant him respite until a time of ease." In both cases, the first wife is not more entitled than you, unless her debt is due and yours is deferred.