@translation check:

can anyone verify this translation:
"Onu biliyorum" - "Mi konas ŝin." (I know her)
?

Yep.
It means both:
Mi konas ŝin.
and
Mi konas lin.

(Turkish doesn't distinguish between the two - "O" means both "he" and "she").

and, "I know THAT" ?

Indeed, I forgot to add that it also means:
"I know that."
:)

Because "o" also means "it", "that".

Having said that, I'm not sure that this is the usual wording for "I know that".

I believe that for that sentence there may be another wording. Please ask duran about
"Onu biliyorum", whether it also means "I know that".

I think that "I know that" would be:
Bunu biliyorum.
But I'm not sure "Onu biliyorum" doesn't mean that, too.

Thank you El. As you said,
HIM,HER,IT,THAT = ONU
THIS = BUNU
HİM,HER,IT are objective pronouns.
THAT,THIS are demonstrative adjective with a noun and demonstrative pronouns alone.
I know him, he is John.= Onu tanıyorum, o John'dur
I know her, she is Mary = Onu tanıyorum, o Mary'dir.
I know it, it is our neighbor's cat. = Onu tanıyorum, o komşumuzun kedisidir.
I know this, but I don't know that. = Bunu tanıyorum, fakat onu tanımıyorum.
I know this girl, but I do not know that girl. = Bu kızı tanıyorum, fakat o kızı tanımıyorum.
I think that's enough for you to understand, Marcelo. Take care.

Duplicates of this sentence have been deleted:
x #2494343