what is "Waiting for table level lock"?

Why I have so many queries when I using 'show processlist '

And my CPU is 600+% used

Is there anything i can do to improve mysql performance? Thanks

Yes, you can change your storage engine from MyISAM to InnoDB - MyISAM only knows table level locking (when it writes to a record, it blocks the whole table), while InnoDB knows row level locking (it locks just the row you are writing to)