Macros are a set of commands or code designed to help automate certain tasks - but, as with a lot of other software, if it falls into the wrong hands it can be used for criminal purposes as well.
Macro malware (sometimes referred to as a 'macro virus') can be hidden in Microsoft Office files, and delivered as email attachments or inside ZIP files. This malware is designed to make use of social engineering to infect devices, by using file names that will entice or scare people into opening them - such as tax demands, invoices or receipts.
Macro malware is easier to avoid than other malwares such as spear phishing or ransomware. By virtue of not running the macros in a Microsoft Office file, the malware will not be able to infect the device.
Being able to recognise phishing emails is your biggest advantage when it comes to avoiding macro malware - do not open emails, links or attachments from unknown senders, or suspicious-looking addresses.