It works because it gives you back some hormones and btw strengthens the walls of the vagina as well as tackling dryness.
As well as being given for dryness and soreness it is for those still sexually active.
The advice on no soap is really tops, btw, I just found that by experience.
(I'm fortunate enough to have a bidet, so can just use warm water to give a good splash, but a shower head can do the job - but in the past I have DIY'd using an old basin of clean water)
(Its always 100% OK to ask for a woman doctor btw, if the problem persists/gets worse do get a swab done and tested)