Refers to kind acts, helpful intentions, or a friendly disposition toward someone. Often used in phrases like 好意を持つ (have goodwill) or 好意に甘える (take advantage of someone's kindness).
He always shows kindness to those around him.
I took advantage of your kindness and got a ride.
Indicates a positive emotional inclination toward someone, ranging from friendly goodwill to romantic interest. Common in expressions like 好意を寄せる (have feelings for) or 好意を抱く (feel affection).
She seems to have feelings for him.
Even though it was our first meeting, I somehow couldn't bring myself to like him.
He has feelings for a female coworker.
I took advantage of my friend's kindness and had him lend me a room.
She secretly harbored feelings for the man.
I wish you wouldn't say things that disregard my kindness.
I'm grateful for my neighbor's kindness.
行為 (an act, deed) and 好意 (goodwill, favor) are pronounced identically but mean completely different things.