If you have your website's backup and want to upload it to your new account at Hostinger, you can accomplish this task in four different, alternative ways:
Upload backup with Import Website feature - It will immediately unpack your tar/tar.gz/zip archive to public_html. The best choice if you have one archive with a size of less than 256 MB.
Upload backup with File Manager (Beta) feature - The upload limit is 100GB.
Upload backup with FTP client - There is no upload limit for FTP
Upload backup using SSH - A good choice if you're comfortable using SSH and your hosting plan is Premium or above