The word “fullness” is used in the active sense to refer to Jesus the Christ being the source of an
outflowing of grace. This pouring forth of grace is translated in various translations as “grace in
place of grace,” “grace upon grace,” “grace for grace,” or “one blessing after another.”  
The amplified tries to capture the meaning of “grace in place of grace” by translating it:

“one grace after another and
spiritual blessing upon spiritual blessing and
even favor upon favor and
gift [heaped] upon gift.”

The concept is that out of his eternal personhood Jesus Christ has given us more grace than
we can handle. The image these words create is of Jesus, the everlasting and eternal God,
giving us something that we will never exhaust, but even then he is refilling our supply, which
is itself endless. John repeats this idea in John 10:10 where he again uses the word “full”:

            “I have come that they may have life, and have it to the full.”

If there is an image from nature that captures the idea of the “grace in place of grace” that is given
to us, it is the picture the waves of the sea moving upon the beach. Wave after wave replaces the
wave before it in an endless flow of provision. It is beyond human comprehension and greater than our ability to manage. We can only receive the grace God has already decided to pour out on us.