At a Spanish funeral, it is customary to express one's condolences to the bereaved family. This can be done by saying "Lo siento mucho" or "Mi condolencia". It is also common to share a memory of the deceased with the family. For example, you might say "Recuerdo cuando..." followed by a story about the person. If you did not know the deceased well, you may simply say "Que descanse en paz". Ultimately, it is important to be respectful and sensitive when speaking to the grieving family. By following these simple guidelines, you can show your support during this difficult time.