The phrase "to place one's stop loss" refers to a trading strategy where an investor sets a predetermined price level at which they will sell their security if it declines in value. Full definition
Then place a stop loss at the location of the cancelled order. (tradingday.com)
You typically would then place your stop loss just above the high or low of the bar that formed previous to the break - out bar. (learntotradethemarket.com)
Fear of blowing out your trading account will cause you to place stop losses on all your trades, thus, in this regard fear is good for the trader. (learntotradethemarket.com)