The Twos are the first "expression" of the elements: Whereas the Aces are the Root or Essence of all probabilities, the Twos are the "pure" expression of the element in a recognizable form. The fire of creativity and power; the initiation of deep connection and relationship; the elegance of balanced analysis; the tides of change that underlie manifestation. In the Twos we recognize the dyadic pair at the foundation of all reality--the yin and yang, inward and outward, radiance and coherence, sameness and difference…the essential paradox that gives rise to all things. The nature of the Twos is still a bit abstract and mystical, a contemplation. This accords to the Golden Dawn association of the Twos with the Sefirot Chokhmah,"Wisdom", above the Abyss in the Supernal Realm and thus apart from creation proper.
In more practical terms when reading with the cards, the Twos often show up as reconcilers between people, events, or one's internal states and outward actions, or their desired separation. This owes to that mystical nature of Two as One, One as Two, the Dyadic Pair. Look for ways that a Two can either harmoniously reconcile or separate based on what cards are associated with the Two in a reading.
Mars in Aries
The Two of Wands brings the fires of passion and power together--the energy and desire to create.
Venus in Cancer
The Two of Cups is the initiation of a relationship between two people or events that bond.
Moon in Libra
The Two of Swords is a coming together of perspectives, often in a stalemate. It is balanced, yet can be compromising for both sides.
Jupiter in Capricorn
The Two of Disks is a seemingly endless turn of "this way, then that" upon itself. When it appears in a reading, it can indicate a condition that goes back and forth without resolution, or a natural cycle.