. . . It is not hidden from you -- that you will require prophets.
Nor is it far from you -- that you will need the distant wise men of the generation to explain it to you. You will therefore be able to do it even in the exile.

This is explained by saying:
It is not in Heaven -- You will not, in the matter of repentance, come to require the prophecy of a prophet.
It is neither on the other side of the sea -- You will also not require the distant sages of the generation to explain it to you.
This way it will be possible for you [to repent] even outside of the land of Israel. It will not pose a difficulty -- as might happen with some commandments -- that necessitates the decision of the sages of the generation, something that will be impossible outside of Israel.
It is in your mouth and in your heart to do it -- to realize, in your heart, both your sin and the G-d you sinned to and to regret; then to verbally confess.