What do these green paragraph symbols mean?

Leo is correct and here's a little more context: we press Enter (Windows) or Return (Mac) to signal the end of a paragraph and that's what we can see in your left column. This is a normal typing procedure that evolved from adding a carriage return on a typewriter to conclude one paragraph and start the next one. 

But a lot of new users press Enter Enter Enter (Windows) or Return Return Return (Mac) as a quick way to achieve vertical spacing, and that's what we see in the right column. As you begin to remove those extra returns ¶¶¶, you'll begin to close up the spacing above "woman do...". If it were my document I would remove all of the extra returns and then add the spacing back in via paragraph spacing. 

~Barb

end of paragraph (return key action).