Phishing is the kind of attack that works by trying to get you to click on links or attachments in emails pretending to be from a company or person that it is not really from, which then either installs malware on your computer or tries to extract some kind of information from you, such as passwords or personal data. Phishing can also arrive by message apps, social media, phone or texts: any communication method can be used. It may even contain personal information about you to make you think it is legitimate, taken from public records or online data breaches.
If you suspect a message is phishing then it is usually best to assume that it is and act accordingly. If in doubt, do not click.