1The space, gap, or distance between two things — the most basic physical sense.
机と壁の間に本が落ちている。
A book has fallen between the desk and the wall.
二つの建物の間に細い路地がある。
There's a narrow alley between the two buildings.
棚と棚の間に少し隙間ができている。
There's a small gap between the shelves.
2A period of time during which something continues. In the patterns 〜の間 / 〜の間に, it expresses 'throughout the time of ~' or 'sometime during ~' — a core N4 grammar pattern.
授業の間は携帯電話の電源を切ってください。
Please turn off your phones during class.
旅行の間、猫は友達に預けた。
I left my cat with a friend while I was traveling.
母が買い物に行っている間に、宿題を終わらせた。
I finished my homework while my mom was out shopping.
若い間にいろいろなことに挑戦したほうがいい。
You should try various things while you're young.
3Between (two parties or things) — used for positions, contrasts, or transactions involving exactly two entities. An abstract extension of the physical 'between'.
山田さんと田中さんの間で意見が対立した。
Mr. Yamada and Mr. Tanaka had a disagreement.
2校の間で交換留学が行われている。
An exchange program is held between the two schools.
親会社と子会社の間で契約が結ばれた。
A contract was signed between the parent company and the subsidiary.
4Among (a group) — used with 〜の間で to describe something circulating or holding within a group (rumors, trends, opinions). Where sense 3 is two parties, this is many.
村人の間でその噂が広まった。
The rumor spread among the villagers.
若者の間でこのアプリが流行している。
This app is trending among young people.
ファンの間ではすでに有名な話だ。
It's already a well-known story among the fans.
5Relations or relationship between parties — connections between people, nations, or organizations, often in phrases like 〜の間の関係 / 〜の間がうまくいく.
両国の間の関係はようやく改善してきた。
Relations between the two countries have finally started to improve.
親と子の間の信頼を築くことが何より大切だ。
Above all, it's important to build trust between parent and child.
あの二人の間はうまくいっていないらしい。
It seems things aren't going well between those two.
6Midpoint, middle ground, or average — a position between two extremes. The phrase 間をとる ('take a middle ground') is common for compromise.
双方の意見の間をとって、妥協案を出した。
We took the middle ground between both opinions and proposed a compromise.
駅と大学の間あたりのカフェで待ち合わせよう。
Let's meet at a café roughly midway between the station and the university.
7(Archaic, あいだ only) A classical conjunctive use meaning 'because / since'. Not used at all in modern Japanese — found only in classical texts, Noh/Kyōgen, and early-modern documents.