It means that the company basically incinerated $23B of company funds in the power generation division.
The company is basically writing off the entire purchase price of Alstom (which came to approx. $17.5B) as well as lots of obsolete turbine inventory.
They had to do this since the company knows full well that the secular downturn in power generation won't subside until 2021, at the earliest. Perhaps Flannery was trying to pretend that this write-off wouldn't be necessary, hence the reason for his dismissal?