What is English Closed Captions on a DVD?

[Muse]

I bought a DVD around a dozen years ago of Reservoir Dogs that has Spanish subtitles and English Closed Captions according to the case. My Spanish is weak. What is English Closed Captions? Is it like subtitles and can I turn it on and off readily like subtitles? I have a few decks hooked up but the one I use all the time is a Sony BDP-S390 Blu-ray player. TIA for demystifications.

 

[TheELF]

https://wiki.umbc.edu/pages/viewpage.action?pageId=67994160

 

[Muse]

https://wiki.umbc.edu/pages/viewpage.action?pageId=67994160

If what they say there is true, my player needs to be connected to my projector using RGB cables, not HDMI. I doubt it is. Hmm.