In forex currency pairs such as EUR/USD, the base currency is listed first. In this case, it is EUR, or euros. The value of the base currency is equal to the value of the pair, which reflects the value of the base currency in relation to the counter currency — in this case the USD or US dollar.

Basis is the difference between the price of an asset and the price of its futures contract.

Volume can refer to an individual trader’s account, or the entire market for an asset. It is the amount of currency invested into the asset made in a specified time.

A margin call occurs when the value of an investor’s margin account falls below the amount required by the broker. A margin call refers specifically to a broker’s request that investors deposit additional money or securities into the account, thus bringing it to a minimum value, known as the maintenance margin.

You cannot open a trade because you do not have enough funds: the amount of free margin is below the required margin. You can reduce the trading volume or deposit more funds through the deposit form.