Norwegian B-1 (Level 70)

In this level, I learnt that the Norwegian word “Planet” means “Plane” in English.
What is a “plane?”

if that translation is correct, a ‘plane’ is an Aeroplane/Airplane, though i’m not sure that translation is accurate according to google and deepl.
or a plane is a term in geometry which seems less likely.

Word Choice: Plane vs. Plain | Proofed’s Writing Tips.
In case this might help.

Dear Sirs

Thank you.