This measures the real rate of return on your principal amount by taking into account the effect of compounding interest.
In the case of Moox, your $MOOX tokens represent your principal, and the compound interest is added periodically on every Rebase event (Every 5 minutes), otherwise known as an 'Epoch'.
Your new principal amount is your then current $MOOX token amount, plus your new rebase token amount. This total amount is what gets calculated for your next rebase rewards.
The Power of Compound Interest - It is important to note that your balance will grow not linearly but exponentially over time.
Taking a compound interest of 0.000943% / 5 minutes:
EXAMPLE:If you started with a balance of only 1 $MOOX on day 1, after a year, your balance will have grown to 2,017,700.93 $MOOX.