What's actually happening
A Full Moon happens when the Moon stands opposite the Sun from Earth's point of view. The lunar face is fully illuminated. A Full Moon in Gemini means the Moon is in Gemini while the Sun is in Sagittarius — the axis of information and meaning, of the particular and the general.
The geometry is one of maximum contrast between the detail and the overview.
What the tradition makes of it
Full Moons are culmination points. What was seeded at the New Moon has enough light on it to be seen. Gemini adds a quality of verbal and intellectual completeness to the culmination: the conversation that was circling finds its form, the information that was scattered achieves a momentary coherence, the thing that needed to be said is said.
The Sagittarius Sun wants the single organizing truth. The Gemini Moon has been collecting variations and exceptions. The tension between them tends to clarify which details are essential and which are the noise that was obscuring the signal.
How to actually use it
Notice what conversations or pieces of information have reached their natural resolution. Have the exchange that the preceding weeks were building toward. Say the thing that has been circling without landing.
This is good weather for communications that need to be precise: the message that needs to carry exactly what you mean without the ambiguity that a more diffuse moment might excuse.
When in doubt
Ask what has been said around a subject without yet being said about it — and whether this is the moment to say it directly.