A pip is one tick on the price ladder. On most pairs, that is the fourth decimal: EUR/USD going from 1.0830 to 1.0831 is one pip. JPY pairs cheat by sitting at the second decimal, so USD/JPY from 150.42 to 150.43 is also one pip. Many brokers tack on a fifth decimal called a pipette, a tenth of a pip, used when spreads are quoted very tight.
What one pip is worth in your account currency does not come from the pair name. It comes from the lot size and the quote currency. A standard lot on EUR/USD: around 10 USD a pip. A mini lot: 1 USD. A micro lot: 10 cents. Once the quote is not USD, the broker converts at the live rate and you land a hair off the round number.
The useful thing about pips is that they let you talk about every instrument the same way. A 20 pip stop loss is a 20 pip stop loss, whether the position is a nano or ten standards. The dollar amount changes. The shape of the position does not. Strategies designed in pip terms travel cleanly between account sizes and instruments without rewriting the rules.