Halaal is to intentionally make a wife marry another man intentionally to divorce her so that she can marry again her previous husband to comply with rule that divorced woman can not go back to her husband until she marries another husband and divorce her , then she is can come back to her previous husband.
Halaal is a forbidden action done mostly by Indians, Pakistans and some other Fake Muslims who manipulate the Sharia of Islam and they follow Satanic ways of doing things with aim compliance with Sharia. if the husband and wife thinks they want to come back together after divorce but the wife never marry again, they hire a man who intentionally and knowingly marries her on contract to divorce her after agreed period so that she can marry her previous husband.
Those who do these forbidden actions, they will pay the man to do so and some times collaborate with corrupt Imams who perform this forbidden kind of Nikahs.
WARNING
Whoever is involved in actions of Halaal is not a Believer but he remains a Muslim, he is going to hell for his or her action of Halaal. Halaal is actually intended adultery by adults with consent of husband and wife, allowing another man to sleep with her so that he can marry her again.