DNS stands for "domain name services." In effect, DNS is the "phone book" of the Internet, translating easy-to-remember domain names into harder-to-remember IPv4 and IPv6 addresses.
Every device connected to the Internet boasts a unique IP address that other online devices use to communicate with it. When a user types a domain name (e.g. thehomeofthefuture.com) into a browser, the browser finds out to which IP addresses (e.g. 126.96.36.199 or 2001:db8:85a3::8a2e:370:7334) that domain name corresponds. It then asks the devices attached to those IP addresses for the information being sought.
Put More Simply...
DNS is the equivalent of you putting your friend Edward’s phone number into your phone under “Edward,” and then pressing “Edward” each time you wish to call him rather than manually typing in his number.
The name “Edward” becomes a shortcut to the 123.456.7890 number that is stored in your phone.