Is knowing a language just having enough visual memory of what’s being said?

I know 2 languages, portuguese and english.

I never gave a thought of this, until I decided on my own to learn a new language, which is japanese.

But here's my 2 cents.

I never think in portuguese how I want to say how to structure the words conjugate the verbs etc.

And I've reached that same level in english, and it was through immersion on youtube movies social media news etc.

But i'm wondering if this whole speaking a language isn't just associating words with visual imaging in our brain.

As I learn japanese, I try to make sure when reading and listening sentences or words, to imagine a picture of it. And that same goes in portuguese and english but it's more subtle not so forced like in japanese.

The words and sentences I can actually force imaging in my brain get better retention than just trying to memorize a kanji or a complete sentence