Hauptmann is a German word usually translated as captain when it is used as an officer's rank in the German, Austrian, and Swiss armies. While Haupt in contemporary German means 'main', it also has and originally had the meaning of 'head', i.e.

What rank is a Hauptmann?

While Haupt in contemporary German means 'main', it also has and originally had the meaning of 'head', i.e. Hauptmann literally translates to 'head-man', which is also the etymological root of captain. It equates to the rank of captain in the British and US Armies, and is rated OF-2 in NATO.

What is KptLt?

Kapitänleutnant, short: KptLt/in lists: KL, (English: captain lieutenant) is an officer grade of the captains' military hierarchy group (German: Hauptleute) of the German Bundeswehr. The rank is rated OF-2 in NATO, and equivalent to Hauptmann in the Heer and Luftwaffe.