OK, thanks.
That is OS X Mavericks. There haven't been any updates to Mavericks for quite a while. Depending on which model Mac you have, you can upgrade to a newer version of macOS, but it won't appear in Software Update. You will have to use links from Apple's website to upgrade to a newer version via the App Store application. Of course, you will probably have to update/upgrade some of your purchased applications as well, depending on which version of macOS you upgrade to.
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