When you begin pronouncing words or phrases with ㄹ as the initial sound of a syllable, it resembles /l/ with your tongue lightly touching the teeth ridge. These days, due to the influence of English, for loanwords, some people pronounce them with /l/ while others pronounce them with /r/.
라디오
라면
라이터
When ‘ㄹ’ occurs in the middle of a word or a phrase as the first consonants of a syllable, it is pronounced as flapping. Flapping is the sound produced when the tongue tip quickly touches the teeth ridge. In English, for example, /t/ as in ‘writer’, ‘city’, and ‘butter’ exhibits the same phonological phenomenon. However the sound of Korean flapping is not identical due to a slight difference in the place of articulation.
보라
다리
미로
나라
The initial sound of a syllable after the batchim ㄹ is pronounced as /l/.