You will now receive a warning from the system notifying you that you're about to burn your tokens in exchange for their backing amount, click "confirm" to continue and then also confirm the transaction dialog which will appear from your wallet regarding the gas fees.
Example:
Say you have a token whose trade value is 10BNB per token and it has a backing value of 2BNB.
If you decide, for whatever reason, to burn 1 such token, you will receive the backing amount for that token, which in this case is 2BNB.
Ok, so this is very important, you will always receive only the backing amount for burning a token, NOT the trading value (which in this example is 10BNB), keep that mind.