As mentioned in the 訳（わけ）だ grammar point, わけ is a 名詞（めいし） (noun) that is used for strong determination/conclusion in Japanese, in the same way that ‘so’ is in English. Naturally, this determination may sometimes be negative, as is the case with わけではない. ではない being the conjugated form of the 助動詞（じょどうし） (auxiliary verb) だ
, the 副助詞（ふくじょし） (adverbial particle) は, and the い-Adjective
わけではない may be translated as ‘it doesn’t mean that (A)’, or ‘it’s not the case that (A)’. Although, ‘it is not necessarily so that it’s (A)’, or ‘so it’s not (A)’ are closer to the actual nuance of わけ. わけではない can be used at the end of any sentence, so long as the word before わけ is in 連体形（れんたいけい） (attributive form).
It is not the case that I am able to speak Japanese because I live in Japan. I studied Japanese before I came.
It is not necessarily so that my house is big, but it is not small either.
It's not that my job is difficult, it's just busy.
It's not necessarily so that I have a fever, but my body feels heavy.
As always, では may be replaced by じゃ.
That director is famous, but he did not become popular because he directed a movie.
It's not so that I am saying that you were in the wrong. (I am not strictly saying that you were in the wrong)
and わけではない match the explanatory meaning of ‘so’ in English that often replaces words like ‘because’ and ‘since’. However, as we will examine in more detail in the わけがない
grammar point, わけ also matches the emphatic nuance of ‘so’, as can be seen in statements like ‘it’s SO not (A)’.
It's not necessarily so that I dislike you. (But I sure don’t love you)
I SO don't dislike you. (I don't dislike you at all)