A 'Web Archive' is a file format that archives inside it all the content of 1 web page. There are although file formats that can store more than 1 web page inside it, like the Mozilla Archive Format. A single web page can contain several resources like images, animations, scripts, audio, video, etc., and all that will be stored inside the respective Web Archive file format. Some examples of web archives are .mhtml, .maff, .webarchive.
References
Web Archives (file format) Wikipedia(Text) CC BY-SA