Not a silly question at all.
A spiritual director is someone you can discuss your spiritual life with and see how the Holy Spirit is active in your life.
You mentioned a vocation director and certainly if you are discerning a vocation, a spiritual director is essential. What vocation is God calling you to and how are you responding to that call?
But there are lots of other topics related to your relationship with God, your prayer life, your activities, etc. that can be discussed with a spiritual director.
A spiritual director might be a priest (who can then also be your confessor), a deacon, religious, or lay person.