It is a dash, which has the function of indicating the author/source of explanation.

The functions of dash are as follows:

1. Express explanation

2. Express prolongation of speech

3. Express conversion, jump or change of meaning Turning

4. Express interjection

5. Strengthen key points

6. Examples of branch lines

7. Use before subtitles

8. Indicate the author

9. Supplementary explanation

10. Lead to the following

11. Express the progression of meaning

13. Indicates that the words have not been finished