When something is detectable, you can notice it or find it — even if it is small, quiet, faint, or trying not to be seen.

When something is當某樣東西是 detectable detectable（可偵測的） you can notice it or find it你就能注意到它或找到它 even if it is small, quiet, faint即使它很小、很安靜、很微弱 or trying not to be seen或想要不被發現

We use it a lot with tests and machines: a smell that is barely detectable, a leak that is detectable only with a special tool, a disease that is detectable in a blood test.

We use it a lot我們很常用這個字 with tests and machines來講檢測或機器 a smell that is barely detectable像是一種幾乎聞不太到、但偵測得到的味道 a leak一個漏水（或漏氣）處 that is detectable only with a special tool要靠特殊工具才能偵測到 a disease一種疾病 that is detectable in a blood test可以在驗血中被偵測出來

Though actually, detectable does not mean “easy to notice.” It only means “possible to notice.” Something barely detectable is almost not there; you need a careful look, or a machine, to catch it.

Though actually不過事實上 detectable does not mean detectable不代表 "easy to notice"「很容易注意到」 It only means它只是說 "possible to notice"「有可能被注意到」 Something barely detectable一個幾乎偵測不到的東西 is almost not there幾乎等於不存在 you need a careful look你得仔細看 or a machine或靠機器 to catch it才能抓得到它

The word is common in science, news, and safety talk, and it sounds a little more careful than “you can see it.”

The word這個字 is common常出現 in science, news, and safety talk在科學、新聞和安全相關的話題裡 and而且 it sounds a little more careful聽起來比較謹慎一點 than "you can see it"比起直接說「你看得到」