Without problems there would be no reason to improve.

Improvement needs friction. If nothing ever went wrong, nothing would ask us to change. The quote treats problems not as interruptions of a good life but as what sets growth in motion. A smooth, comfortable situation gives no sign that anything could be better, so we stay as we are. A failed exam or a strained friendship shows a gap between how things are and how they might be, and closing that gap is what we mean by getting better.

The idea fits a long tradition of practical thought. The Stoics, Marcus Aurelius among them, held that obstacles become the material for action, and the proverb that necessity is the mother of invention says much the same. I can't verify who Benjamin C. Jones was, so the attribution is uncertain, and the sentence is best judged on its own merits.

Say someone's presentations at work keep falling flat. They can resent the criticism, or treat it as information: record themselves, ask a colleague for candid feedback, and rework the opening. The problem becomes the reason to build a skill they would never have bothered with otherwise.