How it works?
The long string is simply a binary sequence converted to ASCII. The first for statement makes bstart out at 10, and the [b+++21] after the string yields 31. Treating the string as an array, offset 31 is the start of the “real” data in the string (the second line in the code sample you provided). The rest of the code simply loops through the bit sequence, converting the 1’s and 0’s to !’s and whitespace and printing one character at a time.