Burano is a small island north of Venice. It is a common place for tourists visiting Venice to also check out.
It is famous for its brightly painted houses, and is an excellent place to go while visiting Venice. Check out my venice itinerary which includes a day of visiting the nearby islands (including Burano and Murano).
You can find houses painted almost every colour. Ledgend says that they were painted like this several hundred years ago so that returning fishermen could find their house even if there was lots of fog.
Burano is not just one island (it is a archipelago), and there are four small islands in Burano, which are all connected by bridges. You can walk everywhere and it is really recommend to just turn up to the island and go for a wander. You will quickly start to notice all of the brightly painted houses.
Take the waterbus from Fondamente Nuove. I recommend you get a 24 hour pass and make use of it one day to see more than just this island. Check out venice itinerary for more details.