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If you hesitate, opportunity won't come twice.
Literal
Hesitate-[if-ば] opportunity [topic-は] twice not-come.
An aphoristic advice line. 躊躇 (ちゅうちょ) is a formal noun for 'hesitation' — note the hard-to-write kanji. 機会 (きかい) 'opportunity, chance'. 二度と ('never again, not a second time') uses 度 as a counter for times/instances. The ~ば conditional fits aphoristic general truths. This is the Japanese rendering of a common proverb-style advice.