I was woundering because I want to start taking care of bees for plants.
From your plants or garden's perspective, honeybees are good for pollination which usually means more and bigger fruit. To quote from ' http://www.masterbeekeeper.org/stinging/honeybee.htm ':
'Benefits: Honey bees provide pollination for over 90 commercially grown crops as well as many wild plants. It is estimated that honey bee pollination adds $14.6 billion per year to agricultural output in the US. They also provide over 200 million pounds of honey, as well as a variety of other products such as beeswax, pollen and propolis'
How much benefit depends on what type of plant. Some don't need bees at all (such as tomatoes or corn), others benefit somewhat (strawbearies require 24% insect pollination on average) and other require nearly 100% bee pollination (Almonds for example).
Here is a link that might be useful: Value of Bee Pollination