Questions & Answers about Beni affettin çünkü küçük bir hata yaptım.
How do we know it means "you forgave" and "I made"?
In the past tense, the personal endings are a bit different from the present tense you learned earlier. For "you", we add a simple -n at the very end of the verb, making affettin. For "I", we just add an -m, giving us yaptım.
Why does the past tense suffix look different in affettin and yaptım?
The base past tense suffix is -di, but it changes to match the sounds of the verb root. Both affet- and yap- end in hard, voiceless consonants (t and p), which forces the 'd' to harden into a 't'. Then, vowel harmony kicks in: the 'e' in affet- needs an 'i' (-ti), while the 'a' in yap- needs an 'ı' (-tı).
Why does the sentence start with Beni instead of just Ben?
Beni is the direct object of the verb affettin (you forgave). Because a specific person is receiving the action of the verb, we must add the accusative case suffix -i to the pronoun. So, Ben (I) becomes Beni (me).
Why is it küçük bir hata instead of bir küçük hata?
In English we say "a small mistake", but Turkish word order almost always places bir (a/an) between the adjective and the noun. It literally translates to "small a mistake".