Units on Oanda= Dollars. So he's trading 3 or 4k..
Ignored
Units are not dollars. Units are units.
one unit of euro is one euro, one unit of pound is one pound, one unit of dollar is one dollar.
Wikipedia: "Each currency typically has a main currency unit (the U.S. dollar, for example, or the euro) and a fractional currency, often valued at 1⁄100 of the main currency: 100 cents = 1 dollar, 100 centimes = 1 franc, 100 pence = 1 pound, although units of 1⁄10 or 1⁄1000 are also common. Some currencies do not have any smaller units at all, such as the Icelandic króna."
At oanda you are trading the amount specified in the mainunit of a currency. If you click the "exposure" tab you can see the actual amount of units of the other currency (dollars, euros, yen) that your trade is worth. Since you can trade as small as one single unit you can do very precise and flexible money management even with small accounts and/or use it to hedge something else with the exact needed amount of currency.