The Chiron conjunct Ascendant transit happens when Chiron, the asteroid that marks an old wound and where you end up helping others with the same thing, crosses the exact degree of your natal Ascendant, or rising sign, the face you put forward before anyone knows you. The two act as one thing while the transit is active. What that means in plain terms: something you have always carried privately is suddenly very visible, and the way other people see you is bound up with it.
Because Chiron turns retrograde every year, it often crosses that exact degree three times, and the transit usually lasts several months to more than a year. This is not a quick pass. Chiron makes this aspect to any one natal point once in about fifty years, so if it is on your Ascendant now, this is the only time in your adult life it does this.