it does not mean that ...; it is not the case that
Used to deny a possible interpretation or to clarify that something is not necessarily true. Often follows a clause in plain form. Equivalent to 訳ではない, but more colloquial.
See also: わけではない
Having money doesn't necessarily mean you can be happy.
It's not the case that everything he said is correct.
Combination of 訳 (わけ, 'reason' or 'meaning') + じゃない (colloquial negative of だ). Literally 'it is not the reason/meaning that...', used idiomatically to deny an implication.