Original text - Brasiliaanse Portugees - Oi Thalita

Lilian, do you understand "amiga da arca"?

Yes, Botica, I think I translated that expression as :" vieille amie"

"da arca" means something that dates back to a long time ago.

Arca is a "bahut" where we keep our memories.

I disagree.
I know the idiom "do arco da velha".
I think that "Arca" is a name of a place.

CC: Botica goncin Angelus

As Casper I think it's a name, I have found a wikipédia article.

That makes no sense!

Why would someone make a sentence like that referring to a place?

You don't address a friend saying where she is from.
"I love you so much my friend Casper of/from the Curitiba."

I wrote "the" because the original used "da" which means "of/from the"

As I told you in pm, it could be a name of a church, a shop, a website, whatever.
"Oi minha amiga Lilian do Cucumis."
Does it make sense to you?
But I already asked 27 what she meant by this phrase.