Phishing is when someone sends you spam that looks like it’s from someone else. The goal is to get you to click a link or open a file. This is what a phishing link in an email looks like (click to zoom):
The link there doesn’t go to the right site. All you need to do is hover over the link and look at the little bubble, or look in the lower-left corner of your browser to see if the domain name matches the site. If not, it’s phishing. Don’t click it.