Can you use iCloud to reduce usage on iPhone?

Essentially I have a 16gb iphone with minimal space left and am looking at ways to reduce the usage to fit more on. It says on my usage that iCloud has 5gb of 5gb free? If I were to use that 5gb would it free up space of the 16gb?

To do this you need to back up your iPhone to iCloud, you can do this by going to Settings > iCloud > Storage & Backup and tap "Back Up Now".

After this is done, you can free up space on your iPhone, but only by deleting Apps, Music, Videos and/or Books. Don't worry about deleting things as they are completely free to download again, as iTunes, the App Store etc.keep a record of your purchases.

You can also do the exact same process with iTunes, by plugging your iPhone into your PC/Mac and backing it up to iTunes, then deleting the media you don't want.