This is what usually confuses those who have just started interacting with the Korean alphabet. A number of letters in the Korean alphabet can be converted into a different letter and it occurs when the letter is placed at the end of the syllable. That's why for example, 박 is seen as 'bag' but the letter g is at the end, turning it into the letter k, and this will be pronounced in English as 'Park' (last name for a few known people like Jimin of BTS, Korean actor Seojoon, Seonghwa of ATEEZ) I'll put a list: ㅂ (b) - can turn into 'p' ㅈ (j), ㄷ (d), ㅅ (s), ㅊ (ch) - can turn into 't' ㄱ (g) - can turn into 'k' Also, ㅇ is a placeholder for words that start with a vowel, since a block should have AT LEAST one consonant and one vowel. When it's not being used as a placeholder and is put at the end of a syllable, it is pronounced as 'ng' like '방' in Bangtan Sonyeondan!
So far, these are the ones I know. Anyone is free to add more notes so that we can further help other people! I'm a Filipino and I really believe we should all have hospitality for those who are struggling! We can do this! Fighting!