also: そんなもん · そういうもの · そういうもん
expression, noun
that's the way it is; such is life; that's how things are
Used to express resignation, acceptance, or a matter-of-fact explanation that something is simply the nature of things. Often carries a nuance of 'it can't be helped' or 'that's just how it goes'.
人生はそんなものだ。
That's just how life is.
失敗は成功のもとって言うけど、まあそんなものかな。
They say failure is the mother of success, but well, I guess that's how it goes.
Combination of the pre-noun adjectival そんな ('such') or そういう ('that kind of') with the noun もの ('thing'). The phrase grammaticalized into a set expression meaning 'that's the way it is'.