Why does cutting a steak too soon leave a puddle on the plate?
Slice meat the second it leaves the heat and a pool of juice spreads across the cutting board instead of staying in your dinner.
Heat makes muscle fibers contract and wring out their water. Let the meat rest a few minutes and those fibers relax, the freed juices cool and thicken, so less escapes when you cut. The juice does not soak back in, it just stops being squeezed out. How big the saving is is debated, but the part that is settled is the direction: a short rest costs you nothing and never makes meat drier.
Pan-sear a beef steak, slice it right away, and juice runs out onto the plate. Rest it 5 minutes under loose foil and the same cut holds more of that liquid when you finally cut in.
Give cooked meat a short rest before cutting, so more of the juice stays in the meat instead of on the plate.
A 5-10 minute rest is a free, no-skill way to keep a steak or roast a bit juicier, and the only cost is a few minutes of patience.
Hot meat is a clenched fist squeezing water out; resting lets the fist unclench.
Learn the idea and practice English at the same time.