The Ace of Pentacles (Ace of Rocks in the Penguin tarot deck) represents a brand new financial opportunity, or it can be a new career opportunity. It is also a card that represents manifestation as well as abundance. It represents brand new beginnings in a material world, as it can also represent a new beginning having to do with physical health.
This card can show up when you are about to receive a brand new job offer, or a new business opportunity that is fruitful could come your way. Whether it stays fruitful though will depend on the other cards that surround it. It can also represent a new healthy habit that will add years to your life as well, and it may even represent pregnancy since it has to do with the physical side of things. You could also be getting a new material gift or possession that will be of use to you. Either way, it is a card that represents manifestation for abundance.
When the Ace of Pentacles comes up in reverse it can mean that there was a new opportunity that is now lost as you did not act quickly enough to grab it. It can also be a result of poor or lack of planning and lack of foresight.
The Ace of Pentacles is tied to the earth signs, Taurus, Virgo, and Capricorn, astrologically.