A pip is the standard unit traders use to measure small price movement in many forex pairs. In most non-JPY pairs, one pip is 0.0001; in many JPY pairs, one pip is 0.01. It helps compare movement, stop distance, and profit or loss without only reading raw price decimals.
Basics
If EUR/USD moves from 1.1000 to 1.1001, price moved 1 pip. If a demo trade has an entry at 1.1000 and a stop at 1.0980, the stop distance is 20 pips. The learner should then connect that pip distance to position size, because 20 pips can be small or dangerous depending on the lot size.