How do you explain the comma? What is it for and how is it used?
One of the easiest ways, is to say that is used in writing to reflect the pause you would use when speaking. Although that is simplistic, it does deal with the matter quite effectively.
Please click on the image below to read a very well-written article outlining 10 main uses of this punctuation mark.
I am on holiday now until 03 June, so see you soon.