If this came up in your chart, check the source. The last people born under it are gone, and the next ones are not here yet.
What it looks like in a life
Uranus and Neptune stood opposite each other from about 1906 to 1910, with Uranus in Capricorn and Neptune in Cancer. Everyone born in that window shared it. The next opposition arrives around 2078. Nobody living carries it natally, so if software handed it to you, look again: you are probably seeing transiting Uranus opposite your natal Neptune, or two planets more than twelve degrees apart. The transit version is real and worth knowing. It comes once in a life if it comes at all, and it lands as a stretch of years when something you believed in quietly stops holding and something abrupt arrives to replace it.
The gift
The opposition is the aspect of seeing by contrast. When Uranus stands across from Neptune, the shock and the dissolve illuminate each other instead of blending. You cannot drift, because something keeps jolting you awake, and you cannot stay rigid, because something keeps softening the frame. That tension, held long enough, produces a person who can be radical and devotional at once without collapsing either into the other.
The friction
Two sides that must share one life will take turns running it. The pattern swings: a period of hard certainty and severed ties, then a period of surrender and fog, each one a reaction to the last. Nothing gets integrated while the swinging continues. The cost is years spent correcting for the previous correction.
The esoteric layer
The ancient astrologers knew neither of these planets, so none of this belongs to that tradition. The esoteric framing is Bailey and modern. The opposition is the number two, and esoteric astrology reads it as full moon logic: illumination through the other, the pair of opposites held in tension until a third reconciling point is found. Bailey counts Uranus the seventh ray of ordered change and Neptune the sixth ray of devotion, both sacred, both reaping planets. Opposed, they demand a person who can hold a vision and break for it in the same life.
Where this goes
If this is a transit in your chart, the houses it crosses say what is being pulled apart and when it settles. A full natal reading is where that gets dated and named.
Related
See it in your own chart
Cast your chart free and read this placement next to everything else you carry.