The script that you provided reads a line of data provided by a user into a shell variable named a. It then uses awk to see if the 5th character in the 1st string of non-blank characters is a "5" (presumably the 1st digit in a two digit month is a "5"), and if it is it gets the 6th character from that string, adds 1 to it, and throws it away; otherwise, it prints the string "wrong". In either case, your script then gets a syntax error from the Korn shell because you have an if statement with no matching then nor fi.

Is this a homework assignment?

If it isn't, can you explain (in English) what needs to be done to a string in the format YYYYMMDD to add 9 days to it and end up with a valid date in the same format. If you can't explain what your script needs to do to update your user's input string, you would be much better off using the tools on your system that are designed to perform date arithmetic instead of reinventing the wheel. Even if you can explain the steps required, please explain why you want to reinvent the wheel rather than use system tools that have been written to correctly handle these types of calculations in normal years, in leap years, and (in some cases) even across the conversion from Julian to Gregorian calendars.

And, please tell us what operating system you're using. An operation like this can be performed with a 1988 vintage Korn shell, but some things would be easier with a 1993 or later version of the Korn shell. What version of the Korn shell is installed as /bin/ksh varies from system to system.