1. When used in English, it gives the impression of a surprised laugh. Like saying the words "lol" and "wow" at the same time. In this case it's pronounced "Lahl".
2. More rarely, it simply means "wow" like it does in Polish. It's mainly only written like this if one does not have access to a Polish keyboard. It should be pronounced "wow".
Ex 2: Lal! The weather's really cold today.
Normal Gamer - lål you sad little 13 year-old kid
13375P33X !D10T voted out Normal Gamer
13375P33X !D10T left the game