Two stones side by side are a single chain, and a chain's liberties are counted for the whole of it — that is the whole point of connecting. Five of the six points around this pair are already black, so the chain is down to its final breath on the lower side. One move ends it: fill the shared liberty and both stones come off at once. Leave it for a turn and White connects a third stone behind, and two easy prisoners become a two-liberty group.