​This is an anti-virus and advanced threat protection feature that is free and built in to your Windows 10 platforms.

​Windows Defender Antivirus: Your next-generation protection

Windows Defender Antivirus is the next-generation protection component of Microsoft Defender Advanced Threat Protection (Microsoft Defender ATP). Next-generation protection brings together machine learning, big-data analysis, in-depth threat resistance research, and the Microsoft cloud infrastructure to protect devices in your enterprise organization. Next-generation protection services include the following:

• Behavior-based, heuristic, and real-time antivirus protection. This includes always-on scanning using file and process behavior monitoring and other heuristics (also known as “real-time protection”). It also includes detecting and blocking apps that are deemed unsafe, but may not be detected as malware.
• Cloud-delivered protection. This includes near-instant detection and blocking of new and emerging threats.
• Dedicated protection and product updates. This includes updates related to keeping Windows Defender Antivirus up to date.

To enable this follow these official Microsoft instructions
https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-antivirus/windows-defender-security-center-antivirus