It means the same thing - "concatenate".
But, what it's doing here is changing a Text entry of the name of a month to
an XL recognized actual date value.
If you type
January
in A1 of a new, empty sheet, all you'll see in the formula bar is January.
Now click in A1 again and add
-0 (that's zero, *not* the letter O)
To the end of January, then see what happens in the cell and in the formula
bar.
The formula is doing exactly the same thing by adding (concatenating) the -0
to the text month name, making XL convert it to an actual date.