Risk management is the process of controlling how much can be lost on one trade and across a sequence of trades. It helps keep one mistake from becoming an account-threatening problem.
Position sizing converts your planned dollar risk and stop distance into the amount you should trade. The correct lot size comes after the risk decision, not before it.
Drawdown measures the decline from a previous equity peak. Large drawdowns become progressively harder to recover from, which is why risk control matters across losing streaks.