The Three of Cups (Three of Ice in the Penguin tarot deck) is a social card in the Minor Arcana. This is the card that rules celebrations with a group of friends, as well as collaborations and creativity that involve others. It can also be a card that represents a new family whereas the Two of Cups represent marriage or union, then the Three can be a new baby. That would highly depend on the spread as well.
And the type of collaborations that are represented by the Three of Cups would be creative such as starting a new art project with a group of friends. Or it can represent creative outlets enjoyed with a group of friends such as taking an art or sculpting class. This card represents friendship in general. When this card comes up, it encourages you to get together with a group of friends and have some fun. Indulge in some laughter. This is a very happy card and when this card comes up especially during the time of stress and being overworked, take its advice. Go and have some fun with a group of friends and take a break. You need it to balance your life.
When the Three of Cups shows up in reverse, it can indicate preferring to celebrate anything by yourself. It also represents the need for alone time, or being at the other end of the spectrum, partying too much to the point of destruction.
Astrologically this card is linked to Mercury in Cancer.