The cell was filled in previously and now I want to add data in that same cell. I thought just getting to that point and hitting the enter key would do it, but it goes to the next cell down. I have no idea what the tags mean.
There are a couple of ways to get “back into the cell” for editing.
If you had entered text into the 1st Cell, A1, and typed a long sentence
you would see that the text "seems " to extend into A2, A3, etc.
It is still contained in A1 of course.
If you wanted to add some more text at the end of the line,
you can click on Cell A1 and then click at the end of the original line.
After you have clicked on Cell A1, and then clicked on the place in the
original text where you want to add more text, you can CAUSE the new
text to begin on a “new line” (that is still within A1) by simply pressing
Ctrl + Enter.