At the beginning of a syllalble, it's pronounced "r", and at the end it's pronounced "l". So in this example, the middle syllable 를 is pronounced "reul". There's an exception, though; when there's two ㄹ in a row, like there are towards the end of 베를린, it's just pronounced "l". So 베를린 is pronounced somewhat like "be.reul.lin". Hope that helps a little bit?
It varies depending on which vowel accompanies it. Sometimes it sounds more like an "l," sometimes more like an "r." It's a common theme among Asian languages, and is the reason they have as much trouble differentiating those letters in our language as we do combining the sounds in theirs.
It can also vary by region, some areas will pronounce words with more "l" character, some with more "r."
The same can be said for "g" and "k," "b" and "p," and "d " and "t."
Don't worry if it seems really confusing at first, I still have some trouble with it too. Just something that comes with hearing the words over and over, and trying not to get too hung up on the Romaji "equivalents."