Windows 10 has Windows Security with anti virus, firewall and other protections. There is an icon for it in the Notification Center on the right of the Taskbar.

Mary is spot on with her recommendation. And Windows Security has improved greatly since it's early introduction as Windows Defender. PCMag has it rated good and I have also seen it as one of the top 10 antivirus programs of late. I would also suggest pairing it with Malwarebytes Free for an even higher level of protection. That can be found here.