this is mean we have max 1000 sat/b "1 MB" right?
Today, when I check my blockchain wallet, found this numbers.
Can anyone explain why I get this numbers?
All it's saying there is that you can't afford to use that fee because your balance isn't big enough. 1k sats/byte is probably unnecessary, i think 800 sats/byte should be fine for a small to medium sized transaction to confirm within a few hours.
Nothing to do with the block size whatsoever.
These numbers are simply from blockchain.info's recommendations for the best fees to pay in order to get your transaction confirmed within the first block or in the first 6 blocks, similar to what you get in electrum and other wallets.