Unless you do something unusual, that's almost exactly what it means. (Almost exactly because new causes appear, and those chances won't stay constant during your life.)
US population: 330M
Deaths per year (approx): 3.46M (call it 1% of the population)
2.5% of deaths: 86,500 people
Number of flu infections, per year: 9M .. 41M
2.5% chance of dying of flu: 225,000 .. 1,025,000 people
Number of deaths due to flu, per year: 4,900 .. 51,000
Actual chance of dying of flu (2010-2022): 0.01% - 0.5% [0]
[0] min ((4900/41000000), 4900/9000000)) .. max (51000/41000000, 51000/9000000)
> the IFR of the seasonal flu is around 0.1%
We're all going to die some day. Based on current causes of death, there's a 20% chance, give or take, that it will be heart disease. A 20% chance it will be cancer. A 2% chance one of us will die from kidney failure. And around a 1.5% chance it will be from the seasonal flu, which has an IFR of 0.1% or less.
Anyway, bringing this back around to the Spanish flu, it's fascinating, to me, that if you were alive in 1918, there was around a 1% chance you would die, that year, of the Spanish flu, and around a 2% chance you would die, years or decades later, of a seasonal flu. Pandemics get you upfront, all at once, epidemics get us eventually, over time.
"If you die, then the cause of death is to 2.5% the flu" is one meaning. Likely close to correct.
"With 2.5% you will die this year a death caused by the flu" is another. Unlikely to be correct.