Currencies are not traded on the various foreign exchanges in the same way as stocks & shares. In the latter case the exchanges close at a specified hour, each day, after which there is no more trading. So it is clear what the opening and closing prices are.
With currencies there is no regulated exchange. The 'FX market' consists of a network of financial institutions and retail trading brokers which each have their own individual hours of operation. Most operators, however trade between the hours of 8.00am and 4.00pm in their time zone.
But it does mean that the daily 'closing price' in London for each currency will precede by about 5 hours the closing price in New York. But to all intents it is a global market place. By the time London closes New York is open, by the time NY closes Tokyo, Hong Kong and Singapore are open. And by the time they close London is open again. So it is a round-the-clock business.
So the term by the close by itself is meaningless. For relevance it has to say 'By the close in London/New York/Tokyo etc'.
Having said all of that it has been pointed out to me that the OP's article was not at that point talking about the closing price of a currency, but about the Micex exchange. So the closing price would be the price ruling at the time of the close of the exchange for that day's trading.