To view subtitles when watching movies, TV shows, and other videos, subtitles need to be enabled in iTunes before syncing the media content to the iPod:
Enabling Subtitles Languages in iTunes
1. Open iTunes on your computer.
2. Click iTunes in the Menu bar and then click Preferences.
3. Click Playback.
4. Click the entry field for Subtitle Language and select your language choice.
5. Click OK.
6. Sync your media content (movies, TV shows, and other videos) to your iPod nano.
7. After syncing the content to the iPod, turn on Subtitles on the iPod (Videos > Settings > Subtitles).
8. Play your media content on the iPod.