あの大ぼら吹きの話を真に受ける人はいない。
Nobody takes that blowhard's stories seriously.
ほら吹き is the base word meaning 'braggart' or 'someone who tells tall tales'. 大ぼら吹き adds 大 (big) for emphasis, implying an even more exaggerated or habitual braggart.
Common mixed-kanji-kana spelling; ぼら is usually written in kana.
Katakana variant of ぼら; sometimes used for emphasis or in casual writing.
Full kanji spelling using 法螺 (conch shell, tall tale); rarely used in modern writing.
Compound of 大 (big) + ほら吹き (braggart). ほら吹き itself comes from 法螺 (conch shell, also meaning 'tall tale') + 吹き (blowing), literally 'conch blower', referring to someone who 'blows' exaggerated stories.