Your Windows 10 version is quite old and will be out of support soon. That's why it's telling you to update.
Try the following and see if it works.
First of all, take a backup. Before updating, it's good to do so.
Don't worry, your data and apps won't be deleted.
Go to the following website:
https://www.microsoft.com/en-in/software-download/windows10
Click on Update now button. This will download a file.
Run that file and update your computer to the latest build of Windows 10.