The Three of Coins is Earth (wealth, physical items, skills, security, the physical body, growth) related to the element Fire (change, inspiration). It oftentimes represents physical transformation. Dressing up for a formal event, putting up a new trellis near a garden, rearranging one's website to become clearer to the end user— all of these things are in accordance with this card. Because the primary element is Earth, which is connected with growth, the physical transformation in question is likely a constructive one rather than a destructive one.
This card could also signify a project, which makes sense considering that constructive physical transformations are often projects of some kind. In this sense, it can be anything which is undergoing continuous alterations in accordance with some kind of plan.
The Abstract Three of Coins indicates abstract Earth (practicality, dependability, stability, protection) which is related to Fire (desire, identity, ego, moral impulse). This may indicate committing to something— shouldering some extra responsibility which one sees as worthwhile. It may indicate grit and determination where one's commitments are concerned.
Other possible qualities to infer from this card are those of stubbornness and possibly even defensiveness.