"Lefutok az emeletről a földszintre és vissza."

Translation: I run downstairs from upstairs and I run back.

[bnyugat]

How do I know whether they mean 'downstairs' or 'to the ground level' for 'a földszintre' ??

[vvsey]

"Földszint" is always the ground level. That is also its literal meaning.
If you are in a tall building and go down, say, from the 6th to the 5th floor, you say "lemegyek az ötödikre" (to the fifth). Or just "lemegyek X emeletet" (I go down X number of floors).

[clairelanc3]

From upstairs downstairs is no good? Both seem equally strange.

[clairelanc3]

I think you could say "and back" as in Hungarian

[eminens2]

Yes, accepted it. 2021.02.14.