What is espresso powder? Is this the finely ground-up espresso coffee beans (not a coffee drinker)?

Espresso powder is like instant coffee.
Specially selected coffee beans are roasted and ground, then brewed, and then dried.

It's instant espresso, you can usually find it in the coffee aisle...also lasts FOREVER in the freezer, you can also pick up a couple if those Via or Viva instant coffees at Starbucks 2 little envelopes will probably do you fine.