The hierophant, though a ruler, does not share any close relation to the empress, the emperor, or the high priestess, despite all allegorical evidence that would dictate otherwise. As you may have guessed, it is pretty straight forward what the hierophant is representative of. This character represents holiness and divinity. This is not divinity in the sense that the tarot cards themselves hope to attain, but this is divinity in the heavenly god related sense.
The hierophant can often be seen depicted on his card with his right hand held upwards toward the sky in a symbol that is known as the blessing. Usually in this depiction, two fingers on his hand will be pointed upwards, while two fingers will also be pointed downwards. This calls attention to and symbolizes the bridge between heaven and earth. This is sometimes seen as the bridge between heaven and hell, but this is not true. The pope is seen as the greatest connection that god has to the earth, and thus, this is what the hierophant card represents. He alone is the architect of the bridge that brings together heaven with humanity.
The hierophant is also seen in his card seated between two pillars which respectively symbolize law and liberty. It is the job of the hierophant to decide the heavenly laws which shall govern the beings of earth and to interpret religious signs and deliver their messages to all on earth. When the card was invented, the pope himself held a great more power than he does today, controlling huge armies, making his significance much more important in a deck of tarot cards.
The pope card may hold many lofty sounding cultural meanings, but in a normal tarot reading, the hierophant card represents any sort of organized religion that is practiced by the one who is having their reading delivered to them. If they are a Christian, which is one of the most common organized religions, then the pope would have even more significant of a connection due to the connections between him and Catholicism, but many different things can be said about the hierophant card being drawn in a standard spread.
For example, if the hierophant card shows up in the love and relationships area of a spread, this usually means that a relationship will be borne out of religion. Perhaps you will meet your significant other at a church meeting or perhaps they will just be really into your religion. Either answer is possible. If the hierophant is drawn in the business and career section then this means that you may have some kind of religious calling in your work place, or that you should take the way that you do business in a more religious direction. If the hierophant is drawn in the financial area of a four point spread, this could mean that your religion may be the key to your future monetary success. Finally, if the hierophant is drawn in the life and happiness section, this is an indication that a stronger connection to your church will lead to greater vitality and lust for life later on.