I think this is mostly a US thing. Why use yearly salary? You’re not paid once a year, are you? Most likely once a month. Referencing monthly salary makes much more sense.
“I’m making 50k”. Great, now I have to guess - dollars? Monthly? Yearly? If yearly then what’s the monthly paycheck? Net? Gross?
Is 50k per year below average in the US? Is it hard to survive on that amount?
It depends significantly on location and living situation, but 50k ranges from moderately comfortable all the way to poverty line.
To add to the other poster, in the USA we have calculators for these things.
There is lots of info available, but a short answer is:
If you have a family it’s poverty wage.