So you are trying to exchange BNB to BTC?
Do you see the error under BNB box when trying to convert them from BNB to BTC?
It means that if you want to convert them into BTC you need a minimum of 0.05BNB you only have 0.01853403BNB so it didn't work because you didn't reach the minimum of 0.05BNB.
If you want to exchange them into BTC I would suggest you go to trading classic or advanced to exchange them or exchange BNB to USDT/BUSD then buy BTC.
Yes, this is the reason why you can't convert directly your BNB to BTC because you are below their minimum requirement. You can even see it below the tab - minimum amount - 0.05. As suggested by BitMaxz, you can convert it to USDT/BUSD first, however, check if there is a requirement of min of 10USDT equivalent amount of your trade (usually this is the min limit in binance). Because at the current rate of BNB, you only have about 7USD worth of BNB. So it seems, it may not go thru also even converting it to USDT first.