昵 rarely stands alone. Common compounds: 昵称 (nickname), 亲昵 (intimate/affectionate). The traditional form 暱 also exists but 昵 is standard in simplified Chinese.
Sun radical on the left, the indexing radical. The choice is etymological rather than literal - 'intimate' grew from the idea of being 'close enough to share daylight every day'. It files 昵 with 明 bright, 时 time, 晚 evening in the sun-and-time family.
Right side 尼 supplies the sound - ní shifted to nì in the modern reading. The 'nun' meaning is dormant; treat 尼 as a pure phonetic. The same series gives 妮 girl and 呢 particle, all sharing the ní/nì sound rather than the nun image.
