Translation:I teach because I like teaching.
Halo teman! I think the pronunciation is correct. The word "karena" can be pronounced with the schwa sound, and this is because it is originated from the Sanskrit "kāraṇa". So, the vowel e is unstressed, and the first a is stressed, then sounding like "kA-r-na", /karəna/.
Also, "karena" in Forvo:
You are correct. I had my wife read the sentence as she would say it normally, as opposed to speaking slowly for me, and she pronounced karena as kar'na, which is how it normally sounds when I hear it said in Indonesia.