The Thai way of telling the time takes a little getting used to, as it's very different from English and other European languages. Thais do use the familiar 24 hour military time system to some extent, for example for official announcements, but in every day life a different and uniquely Thai system is used instead. The easiest way to approach it is to recognise that the Thai clock is divided up into roughly 4 blocks of 6 hours each rather than 2 of 12, and that each of these blocks of time is referred to in a different way.