The gondolas are pretty traditional boats from Venice and they are propeller by a man with an oar.
This kind of boat was designed exclusively to the Venetian population, because it was a popular way of transportation in old times, also the way how it was built was specially to move in Venice.
Gondolas has a flat bottom to avoid any issue while in the streets, they are black and are drove by a gondolier (driver), they were very popular long time ago but today they are mostly use for the transportation of tourist.
The Gondola is the symbol of Venice, which is pretty elegant and can be drove pretty easy by a man. Gondolas cannot by drove by women because of the traditions of the city.
A more technical definition will say that the gondolas are a simple hull with a plain bottom, an ornamented arc and a simple stern. This arc generally carries a ferro at its end that is why people say that is ornamented.
Gondolas were the usual transportation vessel that the populations of Venice uses, but today that have changed because they are pretty expensive to ride and they are used know for tourism or in weddings, or as a sailboat.