啰 is a colloquial sentence-final particle, a softer cousin of 了. It adds a friendly, reminding tone and is very common in casual speech and southern dialects.
usage
Same character, different word: read luō when it means 'long-winded', as in 啰嗦. As the sentence-ender here it is the light neutral-tone lo.
Left indexing mouth radical 口. It marks 啰 as a vocal particle, something said rather than meant. The same radical anchors the family of sentence-final and exclamatory characters: 吗, 呢, 啦, 哦, 嘛, 哇.
Right component supplies the sound: 罗 luó reduces to a light lo in particle use. 罗 itself pictures a hand-net spread to catch birds; here it is purely phonetic. The same phonetic drives 萝, 锣, and 箩.
