A proverb warning that a little knowledge or untrained technique can cause serious trouble — 'a little learning is a dangerous thing.'
電気工事は自己流でやると危ない。生兵法は大怪我のもとだから、専門家に頼んだほうがいい。
Doing electrical work by yourself is dangerous. A little learning is a dangerous thing, so it's better to hire a professional.
新しいソフトを触るときは、まず基礎を学んでから。生兵法は大怪我のもとだよ。
When trying new software, learn the basics first. A little learning is a dangerous thing.
スポーツでフォームを間違えると怪我をする。コーチに教わらないと、生兵法は大怪我のもとだ。
If you have the wrong form in sports you can get hurt. Without coaching, a little learning is a dangerous thing.