1A flag — a piece of cloth used as a symbol, signal, or emblem (such as a national or team flag).
国旗が広場に掲げられていた。
The national flag was flying in the square.
審判は赤い旗を振って選手に合図した。
The referee signaled the players by waving a red flag.
チームは勝利の旗を高く掲げた。
The team raised their victory flag high.
2In Buddhism, a pataka (banner) — a religious flag used in temple grounds or ceremonies.
寺の境内に古い幡がはためいていた。
Old banners were fluttering in the temple precincts.
3A banner as an administrative division (used in places like Inner Mongolia) — a regional unit sometimes translated as 'banner'.
内モンゴルには『旗』と呼ばれる行政区画がある。
In Inner Mongolia there are administrative divisions called 'banners' (旗).