Bloatware is all the extra software that comes with a new computer or when you download software. Most of it is not useful to you and will either fill up your hard drive and/or use your memory and slow your computer down.
With a new computer they often include a 30 day trial of an anti-virus program like McAfee, a 30 day trial of Office and either trials of other software or limited editions. If you want to try them this is a good way, but if you already own the product you want to use, remove these and install the ones you really want.
When you download many programs (paid or freeware) they often include in with it check boxes to unselect getting extra things like a different browser or toolbars to add on your browser. Unless you want the specific browser or toolbar uncheck them. If you are not sure uncheck them and you can go to the website for the maker of the browser or toolbar later and get them.
Bloatware will make your computer feel bloated and it will not perform as well as you wanted when you bought it. If you are removing that original bloatware on a computer I encourage you to download and run the registry cleaner in ccleaner (at ccleaner.com) and then you can remove it.
If you do not use the anti-virus program that comes with your machine, make sure you get, install and keep updated a program like AVG or Avast (which are free for personal use) or Norton or TrendMicro or others.