"Na nohou nosíme ponožky."

Translation: We wear socks on our feet.

[BoneheadBass]

"Na" in the meaning of "on" or "at" is followed by the locative case. "Nohou" is the locative plural form of "noha."

[endless_sleeper]

Yep. I will just add that 'nohou' is a remnant dual form that is used with body parts :)

[JanHenke3]

If "noha" is meant as a part of the body.
6. case (o) kom, čem
"nohou" and also "nohách"

[TchernoRR]

I'd like to ask what says, in this sentence, that it's on "our" feet and not just "on feet?

[VladaFu]

Czech does not like possessives the way English does. Be prepared to see many more sentences like this one.

[ruthgrace00]

We don't say 'on feet' in English. We say 'on our feet'.
The exception is 'on foot' which means something rather different: on foot rather than by bicycle or by car.