This is the 6428th most frequent Catalan word.
palmo
"Palmo" in Catalan is a span, the distance between the tip of the thumb and the tip of the little finger when fully extended.
In this sentence, "palmo" is used to refer to a unit of measurement based on the span of a hand.
Li vaig mesurar el tauler amb un palmo.
I measured the board with a hand span.
Here, "palmo" metaphorically indicates a small distance or progress.
Va avançant cada dia un palmo cap a la meta.
Each day he advances a hand span towards the goal.
In this instance, "palmo" is used metaphorically in the expression, suggesting the magnitude of a surprise or scare.