Learn Polish: Znam polski bardzo dobrze. - I know Polish very well.

Znać is used when you know a noun, like a person, place, or thing (in this case, the Polish language). Umieć means to know how to do an action, and is always followed by another verb. If you used umiem, you would need to add an action verb, like umiem mówić po polsku (I know how to speak Polish).

How do we conjugate the verb znać (to know) in this sentence?

It belongs to the -m / -sz group taught in this lesson. To make the "I" form, you take the base verb znać, drop the -ć, and add -m to get znam. For "you (singular)", you would add -sz to get znasz.

Why is it polski here instead of po polsku?

We use po polsku with verbs that describe communicating, like speaking or writing (mówię po polsku). But znać needs a direct object because you are talking about knowing a thing. You just know the Polish language itself, so we use the noun polski.

Why does the sentence use dobrze instead of dobry?