This is how you turn on English subtitles in Vimeo

Please note: You need to actively turn on the subtitles yourself. Here are the steps

1. Open a video
2. Go to the menu bar on the right below the video
3. Click on the button "CC" next to the volume control
4. Go to the settings wheel and choose "English"
5. That's it - you should be able to see subtitles now