Right side
宁 supplies the sound directly — níng to níng, identical. The peaceful, tranquil meaning of
宁 doesn't transfer; it's borrowed purely as a sound marker. The simplified
柠 replaces the traditional
檸 with this shorter
宁.
柠檬 lemon is the everyday compound, a 20th-century transliteration of 'lemon' sound-mapped onto two existing chars.