Learn Turkish: Evde Türkçeyi kendim öğrendim. - I learned Turkish myself at home.

The word kendi (self) takes possessive suffixes to show whose self it is. Because the verb öğrendim means 'I learned', we add the 'my' suffix -m to make kendim (myself).

Does kendim mean I taught myself, or that I learned on my own?

In this sentence, it means 'by myself' or 'on my own'. Using kendim alongside a normal verb emphasizes that you did the action independently without a teacher.

Why does Türkçeyi have a -yi at the end?

The -i is the specific direct object (accusative) suffix. When a language is the direct object of a verb like öğrenmek (to learn), it must take this ending. The y is just a buffer letter because Türkçe ends in a vowel.

Why is kendim placed right before the verb?

In Turkish, the word placed immediately before the verb gets the most emphasis. By putting kendim right before öğrendim, the speaker is strongly highlighting that they learned it themselves.