What she has accomplished has gone.

[keannu]

My grammar book says "what" can be interpreted as "all the things that", but it doesn't explain in which context it can be. What do you think?

gz37
ex)What she has accomplished has gone.
= All the things that she has accomplished have gone.

[5jj]

It's not necessarily all the things, but it is certainly (all) those things that we know are relevant to the time period we are talking about.

[Tdol]

And that could be a single thing.