Yesterday I asked a question in programmer. But when I looked today at my today I saw a 'on hold' beside it inside . Why is it so ?
If you visit the question, you can see that it was put on hold for being too broad, meaning that "there are either too many possible answers, or good answers would be too long for this format" and links are given to the Help Center that explain what on hold and closed questions are and how to deal with them.
One of the comments also links to this Stack Exchange blog post which explains why pro/con or advantage/disadvantage questions aren't a good fit for Stack Exchange.
After reading the help center and the blog post, if you're still confused, you'll need to edit more detail into this question. I'm just not sure what you're looking for, since a lot of information was provided on the question itself as to why, in its present form, it's not a good fit for Stack Exchange.