When an opponent has 10 or less life, if this permanent is an enchantment, it becomes a 3/2 Jackal creature.
Once it becomes a creature, it will not change back into an enchantment if your opponent's life total goes back above 10.
Once it becomes a creature, it is no longer an enchantment.
A noncreature permanent that turns into a creature can attack, and its
abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.