Japanese people often say “Iine”/「いいね」and “IIna”/「いいな」in various situations. These have good meaning and you can translate them into “good”, “nice” and so on. But these nuances are subtly different. I will introduce the difference.
This doesn’t have especially deep meaning and you can say it when you simply think action, state, stuff and so on are good or you agree with something.
A:Would you like to go to a park with me ?/私と公園に行きませんか？
A:I traveled to Kyoto yesterday./昨日、京都に旅行しました。
You can say it when you think something is good, but normally Japanese people don’t say it when they agree with something. This expression includes the meaning that I envy you, I want to do that to tell the truth although I can’t do that or I wish I would do that.
A:I went to Yakiniku restaurant in Tokyo 3 days ago./3日前に東京の焼肉屋へ行きました。
You can say “Iine”/「いいね」when you simply think something is good or you agree with something. You can say it when you think something is good and this has the meaning I envy you.