[M]Believe in Hell as a real, eternal place of punishment for the disbelievers and sinners. (Qur'an 2:24)
[1]Know the descriptions: 7 gates, fire 70 times hotter than worldly fire, boiling water. (Bukhari 3265)
[2]Know the names: Jahannam, Laza, Hutamah, Sa'ir, Saqar, Jahim, Hawiyah.
[2]Know that some believers will enter Hell temporarily for purification, then be brought out.
[2]Know that hypocrites and disbelievers will be in Hell forever.