It is when you pour your carefully crafted milk to create designs such as hearts, apples, and rosettas. Type it into a search engine to see pictures. You can also use etching to create designs on top of your drinks as well.
well first off, let's make sure you know what a latte is. ^^ it's espresso and steamed milk. latte art is when you have fun making your latte. using the perfect shots of espresso with killer crema and manipulating the perfectly steamed pitcher of milk into the cup making a heart or rosetta or other funky things with the froth. in other words.. its like drawing on a blackboard except your using milk as your chalk and the shot of espresso as your blackboard. this post is probably the most useless post considering nordstrom coffee broke it down for you already. so i've just wasted 2 minutes of my life explaining. thank you ^^