+5v or ground

hi everyone! newbie here, im sure one of you here has an idea of these connection,
in this website :--> A simple breakout board <--
in the "X8-6" connection, it says there +5V but in some design of schematic i saw,
instead of "+5V" they use "ground" connection, im confused which is which?
is there anybody can explain this?

X8-1 to -6 requires +5vdc to turn the input on.
Al.

thank you very much al.