Lot is the unit of trading quantity in forex trading. In a standard account in forex trading, 1 lot represents 100,000 base currency.
If the trader's base currency is the USD, then 1 lot represents 100,000 USD. As for the margin required for a single lot in Forex trading, it varies depending on the leverage size and platform chosen by the trader.
The number of lots traded is also an important part of money management and position control. If you are worried that one standard lot is too large, there are also "mini" lots and "micro" lots for you to choose from.
1mini lot = 10,000 base currency (0.1 standard lot)
1micro lot = 1,000 base currency (0.01 standard lot)