I'm using the Lexham Discourse Greek New Testament bundle and have a question. Occassionally I see a black dot preceding a word, but I can't figure out what it means. Most items in the bundle let me click on them and give me excellent explanations. However, this doesn't happen with the black dots. As an example, see below from John 6:

You can see in verse 63 there is a black dot right before "life" in the line "The words that I have spoken to you are spirit and life".
Can someone please tell me what this means?
Thanks!