Every trade has two prices that matter before you even enter: the price that proves your idea wrong, and the price you think it'll reach. The distance to the first is your risk, the distance to the second is your reward. Compare them and you've got a risk-reward ratio. Risk $1 to make $2? That's a 1:2. It's the single number that tells you whether a trade is worth taking.
For education only. Nothing here is financial advice, and trading involves risk.