Some updates require a restart (grey circle with white arrow icon) and all updates require you to authenticate to your Mac as an Administrator before they will install. These updates are only for Apple Mac OS X and Applications. This will not update your third party applications like Adobe Creative Cloud or Microsoft Office.
Operating System Upgrade
Also note that Apple updates will only install for your current Operating System and will not upgrade you to a new OS. For example if you are running Mac OS X 10.9.5, you can not run a software update to install Mac OS X 10.10 on your Mac. If you wish to upgrade your Operating System, you can follow the guide here: