Google can help you to break down campaigns into further ad groups. If you have different keyword groups in an ad group, for example including web, internet and online, Google can divide them in 3 new ad groups for better quality score.
What do they do?
There are two ways of handling this: You will be either sent a link to a copy in the interface where you can have a look at the changes and accept them. Your current campaigns will then be overwritten. Or Google will send you a file and you do the changes in the Adwords Editor Tool. Google will still upload the changes themselves though.

Sandy - sounds complicated to me? How do I know that the changes make sense - I wouldn't be comfortable just accepting a recommendation without being able to judge if it made sense?

Andy