The endplay of a crankshaft it easiest to see when the engine is not installed on the car, or at least doesn't have a clutch on it - the endplay is the distance between the furthest inward and furthest outward that the crankshaft can move in and out of the engine housing. That is, push the shaft as far in as it can go (gently!), then pull it out as far as it will go, and the difference between those distances is the endplay. Engines should have some amount of endplay.
Once the clutch is installed and the clutch bell gap is set, the endplay will be reduced greatly.