to prevent troubles before the event (idiom); to forestall; to nip sth
防 · 6 strokes
Phonosemantic compound. 阝 represents the meaning and 方 represents the sound.
患 · 11 strokes
Phonosemantic compound. 心 represents the meaning and 串 represents the sound.
未 · 5 strokes
Similar to 木 (tree), with extra branches added. Based on the original meaning "tree trunk", now written as 枚. The current meaning is a phonetic loan.
然 · 12 strokes
Phonosemantic compound. 灬 represents the meaning and 肰 represents the sound. Based on the original meaning "burn", now written as 燃. The current meaning is a phonetic loan.
安全工作要防患未然，不能等到出事再补救。
Safety work should take preventive measures; don't wait until something happens to fix it.