This refers to faith, virtue, knowledge, self-control, endurance, godliness, brotherly affection, and love, which Peter mentioned in the previous verses.
Peter speaks of these qualities as if they were people who could change his readers, and he speaks of his readers as if they were cattle or a food crop. This can be translated using the opposites of "barren" and "unfruitful." Alternate translation: "because you have them you will not be barren or unfruitful" or "they will enable you to do much valuable work" (See: [[rc://en/ta/man/jit/figs-metaphor]] and [[rc://en/ta/man/jit/figs-doublenegatives]])
A "barren" animal is one that cannot bear offspring, and an "unfruitful" plant is one that cannot bear food. These are metaphors that describe people who do not do valuable work. If your language has only one word for these two ideas, you can treat them as a doublet and combine them. Alternate translation: "unproductive" (See: [[rc://en/ta/man/jit/figs-metaphor]] and [[rc://en/ta/man/jit/figs-doublet]])
You can translate "knowledge" using a verbal phrase. Alternate translation: "through your knowing God and Jesus our Lord" (See: [[rc://en/ta/man/jit/figs-abstractnouns]])