XAUUSD is the market price of one troy ounce of gold quoted in United States dollars. XAU is the ISO 4217 code for gold and USD is the dollar, so a quote of 2410.50 means a single ounce of gold costs two thousand four hundred and ten dollars and fifty cents at that moment.
At retail brokers XAUUSD is traded as a spot contract for difference with a standard contract size of 100 troy ounces. A one dollar move in the gold price is therefore worth approximately one hundred dollars on a one lot position, ten dollars on a tenth of a lot and one dollar on a hundredth of a lot, which is the sizing table every gold trader should have memorised before placing a first ticket.
Because the quote leg is the dollar, XAUUSD carries dual exposure to the gold price and to dollar strength, which is why US real yields, the dollar index, CPI prints and non-farm payrolls all belong in a gold trading calendar alongside central bank purchase data and London and New York session liquidity patterns.