A spiritual counsellor works with questions of meaning, faith, purpose and belief, and with the distress that often arises around them. That covers loss of faith, conflict between a person's beliefs and the circumstances of their life, religious guilt, the difficult process of leaving a faith community, and the particular spiritual dimension that bereavement and serious illness can bring for someone with a religious or spiritual outlook.
An unregulated and widely varying title
Spiritual counsellor is not a regulated title, and practice in this field ranges very widely, from accredited counsellors who have added spiritual specialism to their existing clinical training, through to practitioners holding no clinical qualification of any kind. This range makes it more important than usual to ask directly about training before starting work.
When a mental health condition is present
If someone is dealing with a diagnosed or suspected mental health condition alongside spiritual or existential distress, it is worth checking specifically what clinical training a spiritual counsellor holds, since spiritual support and clinical treatment for a mental health condition are not interchangeable, even where both are genuinely needed at the same time.