This pattern is used to express a logical conclusion, realization, or to explain the reason for something, meaning 'no wonder...' or 'it means that...'. It connects a fact with a logical outcome. For example: 彼はアメリカに住んでいたから、英語が上手なわけだ。(He lived in America, so no wonder his English is good.)

当然の結論や理由を述べる時に使い、「つまり〜ということだ」の意味。例：彼が英語が上手なわけだ。