Why people always say "you better"

Oh by the way,I mean the situation of typing ,not speaking
Especally in my country(which is not a english speaking country)

FelixxxIt should be you have better, isn't it ?

No. You had better.

Felixxxthere is a distinctional meaning of you better ?

No, it is merely an elision of 'had'. In fact, few natives say 'had'—they use 'you'd'.

Thanks my friend!

The idiom is
"had better" + verb: It means "ought to".
You had better listen to the teacher.
In speaking, the "had" is reduced to a contraction: We'd better go now.
And sometimes the "'d" is not pronounced clearly, so you will hear "you better do your lessons.

Otherwise you can say "have better "+ noun, eg "You have better clothes than me."

Hi

In colloquial UK, the 'had' is sometimes lost altogether and we definitely say 'You better'. It's informal, but here's an example ...