안녕하세요!
I just started learning Korean, too :)
A batchim is a term used for "final consonant". For example, 한글 (hangeul) ends with ㄹ which is a consonant, so this word has a batchim; 한국어 (hangugo) ends with ㅓ which is a vowel, so it doesn't have a batchim. You will also see "double batchim" which are batchims like ㅅㅅ, ㅂㅂ etc.
안녕 :)