> Question 1) I want to know what is the mean by 'UnOptimized Read Reqs' and 'Optimized Read Reqs '
physical read requests optimized
Number of read requests that read one or more database blocks from the Database Smart Flash Cache or the Exadata Smart Flash Cache.
> Question 2) Please give me an advice what is 'SQL ordered by Physical Reads tuning'
Are your users complaining about bad performance (with massive physical I/Os as root cause) or are you reaching any I/O sub system capacity? If not - you don't need to tune anything. If yes - take a look at the corresponding SQLs and try to avoid unnecessary physical I/Os (by better application / database design, better execution plans, etc.).