A phrase meaning 'in a good/positive sense' — used to indicate that a comment is meant positively rather than negatively.
彼はいい意味で変わっている。周りを明るくする人だ。
He's different in a good way. He brightens those around him.
あの選手はいい意味で怖い存在だ。実力が桁違いだ。
That player is intimidating in a good way. Their skill is on another level.
いい意味で期待を裏切られた。想像以上に良かった。
I was pleasantly surprised (in a good way). It was better than I imagined.