Every letter makes a different sound at the end of a word. I can't tell you for every single letter, and some letters cannot be the end of a word, but for example words ending in ล,ร,-นท์, -ย์, etc make an "n" sound. The rule is all letters with an alveolar sound change to "n" when at the end of a phoneme. Furthermore, all letters that correspond to palatal and velar sounds are voiceless when at the end of a phoneme. There are more rules to it but I can't think of it right now.
thanks so much, that's really helpful! Do you know what this letter might look like? As mentioned, my university doesn't seem to know anything about it