Great mystery of Rite of Co-forgiveness

It seems to me that God forgives in us,
He seems to enter us invisibly,
The sacrament is made after the Rite
And the grace of forgiveness comes from Him.

And dripping as a drop at the last minute,
You get some kind of amplifying oil,
Immediately happy for some reason.
As God Himself has done: forgive, come on!

They always say this common phrase in church:
"God will forgive, and you grant me forgiveness"
I didn’t understand this phrase at all:
That it's God's Grace in us which gives forgiveness.