What is Buddhism's perspective on "dualism" ?

I have seen alto of Buddhist text and deities mentioning about "non-dualism" or attaining a "non-dualistic" mind (as in nirvana), or rejecting dualism.

What exactly is "dualism" that they're talking about ? like oppositional concepts ? yin and yang?
Why is Buddhism so critical of "dualism" ?

yin and yang is Taoism. do u refer to bud his Thai or chines?

Dualism can have different meanings.
Believing that we are made up of mind and matter is one version of dualism.
In that sense, Buddhism accepts Dualism.

The other meaning is that everything has opposite counterpart.
e.g. happiness and sadness, anger and love, hard and soft, light and dark etc. etc.
We are living in this dualistic world and we going up and down riding the dualistic wave.

Buddhism offers non-dualistic existence which is Nirvana.

Mind and body are one. The illusion that they are dual causes suffering.

Cartesian dualism has been debunked, and its assertions caused much suffering. Dualism was the core metaphysical assumption of the Spanish Inquisition (the body is a cage for the soul, liberated through torture).

Such dualism is also the assumption of asceticism, where the body is tortured to benefit the mind. The Buddha walked that path and rejected it as a fruitless extreme, promoting instead "the middle path". The first monastery founded by the Bhodidarmha is the Shaolin Monastery, famous for its Jung-fu. This practice was adopted as the body must be disciplined and healthy in order for the mind to share these traits.

Dualism can also lead to needless mental chatter and suffering. It is also an ego-based perception (subjective).