The Languages preferences allow you to specify the default text encoding for web pages, the default encoding for submitting forms, and whether or not OmniWeb will request web pages be returned in your language of preference. Generally these preferences are of most use to users who view pages or submit forms in non-English languages.
The Languages Preferences pane.
Assume pages use text encoding: Allows you to choose which encoding OmniWeb should use for pages that do not specify one. At any time you can temporarily change the encoding used for a page using the item in the menu.
Submit forms using text encoding: Allows you to choose which encoding OmniWeb should use when submitting forms. Generally you will change this only of you enter text in non-Western languages.
Request web pages in my preferred language(s): With this enabled, OmniWeb will communicate to web servers the languages specified in the International pane of System Preferences, and their order in the list (indicating order of preference). If the web server has a version of the page available in one your preferred language(s) they will send that version of the page instead of using the default language for the site, if supported.