National Flag
noun
A country's flag is the flag they use for their nation. It's the national flag.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. The こく gets shortened to こっ, though, so look out for that.
日本の国旗には白地に日の丸がかかれています。
The Japanese national flag has the sun drawn on a white cloth.
世界の国旗クイズで友達と盛り上がりました！
My friends and I had a lot of fun with a world flag quiz!
オリンピックでは選手たちが国旗を背負って入場します。
At the Olympics, athletes enter carrying their national flags.
やっべーな。お前この巨大国旗を買ったのかよ？いったいどこに掲げるつもりなの？
No way! You bought this huge national flag? Where the heck are you thinking of putting it up?