If I had to venture a guess, it’s kinda like getting dirt removed from the energy.
All kinds of things can introduce variability that is imbalanced—things could be too stagnant or too active (these would be tamasic or rajasic qualities). When the predominant qualities are not in balance, different elements can get pushed to where they don’t belong and this can create weird colorations/imbalances in the energy. Ojas, in some sense, is strengthened when harmony is introduced and balance (sattva) predominates.
When balance/sattva predominates, it’s easier to recognize spiritual truths (i.e. your sense of wellbeing will be, to a greater extent, related to spiritual things).