At the top of your Prime Account there is an overall overview containing the global information of your account. This box is divided in three sections.
This is the most straightforward value: It shows the total value of what you have borrowed. Of course, the nominal value of your borrowed funds don't change, except for interest: 1 AVAX borrowed means there will be 1 AVAX (+ interest) to pay back. The dollar value can differ, depending on what you have borrowed.
All Prime Accounts get their borrowed value incremented with their interest whenever someone interacts with one of the liquidity pools.
While the health meter is a bit more complicated, the basic idea is straightforward: 100% means the Prime Account is perfectly healthy; 0% health means it is insolvent (and will be liquidated). Liquidation means that part of your borrowed funds will be force-repaid, for which you will be paying a liquidation bonus.
Click on the blue words for more information on the Health meter, how to calculate health, or how to interpret it.
Lastly, there is the collateral value. This is calculated as the total value of all assets, minus the cumulative value of borrowed assets. If you have nothing borrowed, it is simply the value of all your assets. The more collateral in your Prime Account as opposed to borrowed funds, the healthier your account. The tokens in which your collateral and borrowed funds are allocated play an important role too though. Read more about how Borrowing Power and Health works.