Error 1064 shown with MySQL

Hello,

I am doing a research on MySQL and the error messages but concerning this particular error below I did not see much information. I would like some experts here to tell me all I need to know about the error from MySQL shown below.

Thanks.

An error has occurred

Query failed ALTER TABLE leads modify colum website Null::MySQL error 1064

You have an error in your SQL Syntax, check the manual that corresponds to your MYSQL server version for the right syntax to use near NULL at line 1