What is the meaning of Sitten?

past participle of sit; alternative form of sat.

Seated.

Settled; stationary; not easily stirred or moved.

plural simple present of sit

then (soon afterward; next in order of place)

when, (when)ever (with the conjunction kun)

then, in that case

Used for emphasis, often without any additional meaning.

used to emphasize or intensify questions

acts as an emphatic modifier for tahansa ... (-kin) expressions used to mean "whatever", "whoever"...

since

superessive singular of sitt

to sit

to sit, to be seated

to sit down

to settle (of a sore)

to be located, to be present

to reside, to live

to sit

to sit

to be situated, to live

alternative form of sitzen

Source: wiktionary.org