Standard elastic travel means the binding can flex a moderate amount (roughly 15–25mm sideways and 10–15mm vertically) before it releases your boot. Think of it as the binding's shock absorber — it gives a little under quick forces so your ski stays on through bumps and chatter, but still releases when you actually need it to in a fall.
This middle-ground option is ideal for most all-mountain, freestyle, and general resort skiers. It strikes a solid balance: you won't pop out of your bindings unnecessarily, yet you can trust them to let go when the forces get dangerous.
If you're not racing at high speeds or charging aggressive freeride lines, standard elastic travel is likely all you need. Only consider high elastic travel if you're consistently skiing fast enough to experience inadvertent releases — and know that lightweight touring pin bindings have less elastic travel, which is a trade-off for the weight savings.