You can't translate AOL emails because the software doesn't feature this possibility. There has been a post on the AOL UserVoice page where users recommended to AOL developers to implement something which Google already did for their products.
You have to email those emails to another service and then use the translation services available to get them into another language. The best way is to use Chrome and select text then translate. Chrome will automatically detect when you have a text in a different language other than English.
