Hey Dear you must write your topic in details.So that it can make a scene and we can solve or learn from you.But it's very disappointing to see your topic which is not fully described.
So First focus on your writing then it will be meaningful and a good contribute for this forum.
Op is asking about something related to this blockchain explorer btc.bitaps.com mentioned in topic title.
It seems he is a new comer to the crypto club. Don't be so harsh with him.
The optimal fee you see is calculated based on the fees of the transactions added in the actual block and maybe compared to other fee rates during a determined period of time. Maybe you have noticed that the lowest value among the three values of optimal fee is categorised as the best fee.