A more thorough explanation:

A permanency hearing is a legal proceeding held to determine the future, permanent status of a child in foster care. This hearing is held under the Adoption and Safe Families Act and must occur within 12 months of a child's being placed in foster care. The purpose of the hearing is to determine the final direction of the case, whether that means going forward with termination proceedings or continuing plans for family reunification.

For example, if a child has been in foster care for 12 months, a permanency hearing will be held to decide whether the child should be returned to their family or if their parental rights should be terminated so that the child can be adopted.

Another example is if a child has been in foster care for 6 months and the parents have not made progress towards reunification, a permanency hearing may be held to determine if the child should be placed with a relative or if termination proceedings should begin.