You must be careful online to avoid an attack though the internet. A malicious website, an infected file or an attacker can steal your personal data without your knowledge if you don't apply the necessary recommendations. Unfortunately, this is not only risk.
It is important to protect your device with a dedicated antivirus program and by learning how to stay safe online. Here are some articles you should read:
For a list of the best antivirus to use, see this article: https://ccm.net/apps-sites/software/3969-the-best-free-online-antivirus-scanners/