One must have the belief in Allah’s Angels, i.e., that they exist, and they are honorable slaves of Allah.  They are neither male nor female.  They do not eat, drink, sleep, or reproduce. They do not disobey Allah’s orders and always do what they are ordered. Allah ta^ala said in Surat at-Tahrim verse #6:

﴿عليها ملائكة غلاظ شداد لا يعصون الله ما أمرهم ويفعلون ما يُؤمرون﴾ سورة التحريم

The verse means: [over which are [appointed] angels, harsh and severe; they do not disobey Allah in what He commands them, but do what they are commanded to do]

The one who says that angels are females is judged with blasphemy (kufr). Allah ta^ala said in Surat an-Najm verse #27:

﴿إن الذين لا يؤمنون بالآخرة ليسمّون الملائكة تسمية الأنثى﴾ سورة النجم

The verse means: [It is those who disbelieve in the Hereafter who name the angels with the names of females].

The angels may take the image of men, but without having the male genitalia.