私は日本語をまなびます。(polite form)
私は日本語をまなぶ。(dictionary form)
I will learn Japanese.
Japanese sentences always end with the verb, which is totally different than English. You really can't do a direct translation, so you don't need いる in this sentence, , either
私は 日本語 を まなびます
は marks the topic of the sentence
を marks the object of the sentence
As for me, I will learn Japanese