Please follow the steps below.
1. Get the Spanish language file and save it as amazon-auto-links-es_ES.po
2. Open it in POEdit.
3. Press Control/Command + F and find the inappropriate translation.
4. Enter your new translated text and save the file. It will create a .mo file as well.
5. Replace the new .po and .mo files with the existing ones located in the wp-content/plugins/amazon-auto-links/language
directory via FTP or File Manager.
Please keep in mind that your modifications will be lost after plugin updates. If you don’t want to repeat replacing files manually every time you update the plugin, you can submit your translation files to the GitHub repository with pull requests.