Phishing is a form of “social engineering”. It’s when you see an email that maybe you expect to see, but it’s not from who you think it is. Phishing emails typically have one purpose: make you open a link or an attachment. Either way, the ultimate aim is to use the link or attachment to infect your PC with malware, usually “zero-day” malware which will often bypass anti-virus software.
To that end, it’s extremely important that you’re suspicious of any email that asks you to open a link or attachment. That doesn’t have to mean a blanket ban – but take extra care to check that the sender is correct and the context of the email is relevant.