There is no widely recognized or official application specifically named "Yaps209 sign apk." This name likely refers to a specific or a package name (like a build identifier) of an existing APK signing tool.
Instead of downloading unknown files like "Yaps209," use these verified options: Download Yaps209 sign apk
Be wary if the app asks for excessive permissions, like access to your contacts or SMS, that it doesn't need for signing files. There is no widely recognized or official application
If you are looking for a reliable way to sign APK files on Android, What is "APK Signing"? What is "APK Signing"?