Here's an interesting difference about how Excel Online treats multiple lines within versus Excel Installed.  If using Alt+Enter to insert more than one line with one cell in one row, when the entry is copied and pasted into an Worksheet that's using Excel Installed version, it creates a cell that is split.

This may be fine, depending upon what's been done, but if you are copying data from an online Worksheet into an installed Worksheet and want to try the content as a true dataset, you may be setting yourself for more work than hoped.

In the clip below, in Cell A1, 3 entries were added and Alt+Enter was used at the end of the first 2 entries to push the text down to look like it's on a separate line:

Then after using Copy and Paste from the online Worksheet into an installed Worksheet, there's a difference.  Row 1 has now been altered to instead be 3 Rows (notice the gray borders): 

When reviewing a list of entries, sometimes it's helpful to quickly count how many of your cells contain text.  For example, when collecting a list of potential attendees to an event.

To do this, click into an empty Cell where you want the result to be displayed.  Then enter:  =Countif(A2:A25,"*").  This function will know that you want Excel to review all Cells from the range of A1 to A25, look to see which Cells have an entry of any time, and with the count these to result in a total number of signed-up attendees.