More information to come later, but in brief: DNS (Domain Name System) is a way of converting a known name such as google.com to its IP (Internet Protocol) Address, such as 74.125.195.101.
Your ISP provides a DNS server that is automatically configured at your router and will provide up the IP Address of every site you request. Some third party DNS services do the same, except they won’t provide the IP address of known malware sites, adding an extra layer to your antivirus. Other DNS servers take this a step further and won’t provide the IP address of known advertising sites which can reduce the clutter for your web browsing and some apps.
I personally use Quad9, which doesn’t serve known malware sites. You would need to configure your router DNS setting with this information:
NextDNS is also a good option and can also block advertisers as is ‘Pi-hole’ which is a something you run on a mini server at home.