echo by itself displays a line of text. It will take any thing within the following "..." two quotation marks, literally, and just print out as it is. However with echo -e you're making echo to enable interpret backslash escapes. So with this in mind here are some examples
INPUT: echo "abc\n def \nghi"
OUTPUT:abc\n def \nghi
INPUT: echo -e "abc\n def \nghi"
OUTPUT:abc
def
ghi
Note: \n is new line, ie a carriage return. If you want to know what other sequences are recognized by echo -e type in man echo to your terminal.