I found this summary on a Facebook group. Their explanations are pretty much accurate it seems.
You may have seen headlines claiming that “Sandie Peggie won her case against NHS Fife.”
Unfortunately, most media reports have left out the key facts and in doing so, have given a very inaccurate picture of what actually happened.
Here are the facts from the tribunal’s own findings:

What the tribunal actually decided
The tribunal dismissed the vast majority of Ms Peggie’s claims, including:

All claims of discrimination

All claims of victimisation

All claims of harassment by Dr Beth Upton

Every allegation made against Dr Upton
The tribunal went even further, finding that Ms Peggie herself harassed Dr Upton during the Christmas Eve changing-room incident. They concluded that some of Ms Peggie’s comments were impermissible manifestations of her beliefs and amounted to harassment related to gender reassignment.
The judge also criticised messages Ms Peggie had written about Dr Upton in a private online chat, stating that some were indicative of trans-phobic views and went beyond expressing a belief, becoming personal attacks.

What Ms Peggie did succeed on
Ms Peggie succeeded only on a few narrow procedural points about how NHS Fife handled the situation, not its policies.
Specifically, the tribunal found that NHS Fife:
Took too long to investigate allegations
Referred to patient-care concerns in an inappropriate way
Mishandled instructions given to her
Should have put a temporary rota solution in place so she and Dr Upton did not need to use the changing room at the same time while rotas were being adjusted
These procedural failings were deemed to have the effect of harassing her but they do not amount to discrimination, nor do they mean she “won” the case in the way many headlines suggest.

On the use of facilities
The tribunal was crystal clear:

It was lawful for NHS Fife to allow Dr Upton, a trans woman, to use the women’s changing room

It remains lawful to allow trans staff to use facilities matching their gender identity, depending on circumstances

There is no evidence that a trans woman poses any greater risk in a workplace changing room than any other woman
This directly contradicts the narrative being pushed by parts of the media and by anti-trans campaigners.

The bottom line
This case was not a legal victory about sex-based facilities or “proving” discrimination.
It was a narrow finding that NHS Fife made some procedural errors, while at the same time:
Upholding the rights of trans staff
Rejecting all discrimination and harassment claims
Finding Ms Peggie harassed Dr Upton, not the other way around
Ms Peggie has the right to appeal the decisions made by the Employment Tribunal, so this may not be the last word on this case.
Ms Peggie had already started separate legal action against managers at NHS Fife, and against the Royal College of Nursing, which she may continue with.
Any media framing this as a broad “win” for Ms Peggie or as a ruling against trans people using appropriate facilities is simply not reporting the reality of the judgment.