"I have not yet understood that function."
Translation:Saya belum memahami fungsi itu.
The correct spelling is "paham", but it's an intransitive verb, so you'll have to use "tentang" or "akan" after it. Saya belum paham tentang fungsi itu.
Oh thanks for the explanation :) I didn't know it's spelled with p, because in Malaysian they spell it with f I think. And in Jakarta they say "ngerti" instead of "mengerti". Is that a real word or just slang?