It's actually not a bee but a hoverfly (family Syrphidae).

Hoverflies are mimicking (look similar like) venomous insects (for example wasps and bees), so that their enemies, for example birds, won't attack them, even if they are completely harmless.

You can recognize that they aren't bees because like all other flies they have only two wings plus halteres.

To learn more about how to recognize the different kinds of insects, you might read this post.