FX risk is the chance that exchange rates move against you. Your base currency is the one you measure everything in — for most UK investors, pounds. Own a US share and your return in pounds is the share's return plus or minus the dollar's move against the pound, so a share can rise 10% in dollars and still lose you money if the pound rises by more.
Some funds offer hedged share classes, which use currency contracts to remove most of that effect at a small cost; unhedged ones leave it in. A hedged class is a separate line with its own ticker, and hedging removes the currency's gains along with its losses. The app converts every holding into the portfolio currency you set in Settings, using daily exchange rates, so its values and returns already include currency moves. A Pie Chart of your stock portfolio sliced by currency shows where that exposure sits.
The share did its job. The exchange rate undid it.
Educational content only. It is not personal financial advice.