When someone compliments you about something, then it is known as 'flattery' Flattery may either be from the heart (honest) or, it may just be said for politeness. Making appreciative, complimentary and even cliche comments in general may be described in general as, 'polite niceties'.
Supportive is between friends, Flattery is for the purpose of inflating another's ego to appear nice. Flatterers or supporters who espouse an opposite opinion in private are called "Two faced"
Unfortunately, we do not seem to have an exact, one word for this situation in English. Many people say things just to be nice, even if their compliments are not how they truly feel. In this case, they are 'trying to keep from hurting someone's feelings'. The phrase 'keep from' means to prevent. The phrase 'hurt someone's feelings' means to offend or upset someone from what was said or done. Therefore, people in your country often say nice things to keep from hurting others' feelings.
残念ながら、この状況を一言で表す言葉は英語にはないと思います。
心から感じていることでなくても相手を傷つけないように、優しい言葉をかける人は多いです。これは、'trying to keep from hurting someone's feelings'（人を傷つけないようにしている）と表せます。
'keep from' は「防ぐ」という意味です。
'hurt someone's feelings' は「〔言葉や行動によって〕（人）の感情を傷つける」という意味です。
ですから、あなたの国では、'to keep from hurting others' feelings'（人の気持ちを傷つけないように）優しい言葉をかける人が多いということです。
When someone has 'good manners' it means that their attitude is friendly and good natured towards people.
'Being polite' is the opposite of being rude.
The two words you see above are the words we use to describe when a person gives a compliment, normally insincerely. The second word is actually a term. This term is appropriate for informal settings, like talking with close friends or family member. The first word, flatter, is appropriate for formal settings.
Usually, if someone is complimenting you or praising you, it may be due to them acting polite. It is common courtesy to be polite rather than rude, even if it means saying something that is considered polite that may not be completely the truth.
"You look really good tonight"
たいてい、人は丁寧な振る舞いとして人を褒めます。
丁寧に振る舞うことは礼儀です、仮にそれが事実でないことを言うことであっても、です。
"You look really good tonight"
（今日はすごくすてきです）
When you want to make someone feel better about themselves by the way you say things is called 'flattery' like your hair looks good today this would flatter someone and make them feel good
Compliments are the same type of thing as flattery by making nice compliments about their clothes.hair/appearance to make them feel good
Politeness is just being nice and saying nice things to someone
In some situations we must be adults and share a smile even when we dont want to.
We can call this sort of phrase a compliment of flattery. We may not agree or get along with a person but we act in a respectful, nice way.
It sometimes maybe uncomfortable to be respectful or nice but we need to be pleasant and smile at everyone.
It is important to be social and try new things. Talking to people you may not know or agree with may be a good way to be more social.
Courteous= showing politeness, being civil nice and well mannered.
In some situations we must be adults and share a smile even when we dont want to.
（日本では時として、嫌でも、大人になって笑顔を交わさなければならないことがあります）
We can call this sort of phrase a compliment of flattery. We may not agree or get along with a person but we act in a respectful, nice way.
（このようなフレーズは "a compliment of flattery" と言えます。私たちは人と意見が違ったり馬が合わなくても、親切に敬意を持って接します）
It sometimes maybe uncomfortable to be respectful or nice but we need to be pleasant and smile at everyone.
（時には親切に、敬意を持って接するのが難しいこともありますが、愛想良くみんなに笑顔を見せなければなりません）
It is important to be social and try new things. Talking to people you may not know or agree with may be a good way to be more social.
（人と交わって新しいことにチャレンジするのは大切なことです。知らない人や意見の違う人と話すのは社交性を高めるのに良いかもしれません）
Courteous= 丁寧な、礼儀正しい
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