Have you already tried holding your cursor over the squiggly line, or the error symbol?
Please note that it's much easier to get help if you describe the problem. We don't like screenshots without descriptions here. Something simple as "My IDE shows an error on the line number. How do I see the error description?" would already have been much better.
Which IDE also helps.
For example, Eclipse has a tab called "Problems" which lists all the errors in your project, in addition to the "hover" ability mentioned above, and clicking on the red blob in the left margin.
He repaced his skull with glass. So you can see his brain. Kinda like this tiny ad: