"It takes one week."
Yes, basically. 間（かん） is used to specify an interval or period of time. It can be used after a number of days, months, minutes, etc.
Why does it add the third symbol? Can't you just only use the kanji for "one" and "week"
It seems that Duolingo only showed me the first comment, my apologies for the double post
I have never heard anyone pronounce 一週間 as いちしゅうかん - isn't いっしゅうかん more natural?...