explain it please?

is there something similar for really long paths?

Explanation:

This uses brace expansion to create the two filenames (orignal and backup). Brace expansion generates a list of strings with each set of characters given in the braces. For example, "echo a{d,c,b}e" will give "ade ace abe".

In this case there is a blank for the first item and the second adds ".orig" for example:

cp file{,.orig}
Becomes:
cp file file.orig

This will indeed work with directories:

cp long/path/here/file{,.orig}