The Greek text of this verse says (with literal translation word for word):
ἐγένετο Ἰωάννης [ὁ] βαπτίζων ἐν τῇ ἐρήμῳ καὶ κηρύσσων βάπτισμα
Came John the baptising one in the desert and preaching baptism
μετανοίας εἰς ἄφεσιν ἁμαρτιῶν.
of repentance into forgiveness of sins.
The New International Version expresses this fairly literally:
And so John came, baptizing in the desert region and preaching a baptism of repentance for the forgiveness of sins.
Now: what does it actually mean? What is a “baptism of repentance for the forgiveness of sins”?
The Good News Bible expresses the meaning more clearly:
So John appeared in the desert, baptizing and preaching. “Turn away from your sins and be baptized,” he told the people, “and God will forgive your sins.”
Note the changes:
(1) John’s preaching is turned into direct speech.
(2) The word “repentance” is explained: “turn away from your sins”.
(3) It expresses explicitly who does the forgiving: God.
(4) The relationship between the various actions is expressed more clearly: you “turn away from your sins”, then “be baptised” by me, and as a result (of the repentance and baptism) “God will forgive you”.
Now let’s see how we translated it into Toba:
Qama'le naq'aeta ga'me 'uo ca'li Juan jo'ne chilaĝanataĝanaĝaic ue'ta di'me aleua jo'ne totapega't, yiyaĝatapega ga'me jiyaĝadipi qaedi 'ñemaĝadiñe, 'viyelaĝadetot joñe'me Dios, qaedi qonachilaĝa'n, nataq'aen qaedi Dios yapalaĝa't gaa'me loeco.
Which means: “Then appeared John who is washer in the deserted land, he proclaims to the people that they do an about turn, return to God, so that they are washed and so that God rubs out their bad actions.”