This prophecy speaks of a time in history at the end where Spectrophilia (having sex with demons and other spirits) will arise again, much as it did during the time of Noah where angels came in to the daughters of men (aka, women) and had sex with them, which got them pregnant, creating the Nephalim, demon/human hybrids, also known as the giants of old.  However, this demonic activity will be even more intense and powerful than in times past, as the target will be more than just women.  Men will be involved as well.  This activity is already very evident in our world and growing more powerful by the day.