Pawns separated by one file on the same rank are immune to the king: if either is captured, the other runs. Bring the king up and do not push prematurely.
White has pawns on c4 and e4 with a king far away on h1; Black's king is on d6, apparently about to pick off a pawn. In fact it cannot: if 1...Kc5 White plays 2.e5! and the pawn is outside the king's reach; if 1...Ke5 then 2.c5! likewise. Pawns one file apart on the same rank form a unit that protects itself, as long as the attacking side does not disturb it.