Heaven
Paradise
noun, の adjective
This is heaven country. Where is that? Probably just in heaven or paradise.
天国 is the general term for heaven. Depending on the context, it can also figuratively refer to any place that feels heavenly.
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 国 is changed to the reading ごく though because of rendaku. Even heaven changes a little bit.
これは、天国にいる母へのメッセージです。
This is a message to my mother in heaven.
ここは、まるでコスプレイヤーの天国だ。
This is like a paradise for cosplayers.
天国がこんなとこだったなんて、がっかりです。
I'm disappointed that heaven was like this.