Hi Ali_1234-5,
Welcome to Apple Support Communities! We're glad you've reached out for help with this message you're seeing using Safari on your Mac! We're glad to help.
It appears that while you've got the latest version of Safari available for your version of macOS, there are newer versions of macOS and Safari.
Which model of Mac computer are you using? This information can be found under Apple menu () > About this Mac.
If your Mac is compatible with a newer upgrade to macOS, we can recommend upgrading your computer to the latest version. Here's a guide to help, including details about compatibility:
How to upgrade to macOS Big Sur - Apple Support
If your Mac isn't able to upgrade to Big Sur, you may be eligible to install an older version that is yet newer than the one currently installed. This guide has more information:
How to get old versions of macOS - Apple Support
Once your Mac is upgraded to a newer version of macOS, a newer version of Safari will be installed as well. We're here for you if you've got any questions.
Have a great day!