The answer is mostly tradable goods priced in dollars and purchasing power parity (PPP). PPP:
If goods were perfectly tradable across borders, with no trade
barriers or transactions costs, then there would be no reason for
prices to differ. This gives rise to the idea of purchasing power
parity, a theory of exchange-rate adjustment based on the law of one
If the same good sells for one hundred dollars in the United States
and one hundred euros in Europe, then according to the law of one
price the exchange rate between dollars and euros ought to be one. The
theory of purchasing power parity is that this relationship holds for
an overall market basket of goods and services.
Empirical tests tend to show only a weak tendency for exchange rates
to move in the direction of purchasing power parity. This means that
cross-border trade is not nearly friction free. The failure of
purchasing power parity to hold, except perhaps in the long run,
indicates that transportation costs, language-translation costs, and
other factors limit the integration of global markets.
The Concise Encyclopedia of Economics: International Trade by Arnold Kling
Because PPP doesn't seem to hold always and everywhere, people who wish to compare nominal or real GDP across countries in a way that avoids the nuisance variation of transitory fluctuations in exchange rates report PPP NGDP and PPP GDP rather than RGDP and NGDP at exchange rates. This amounts to pricing tradable good at their prices in current exchange rates but correcting for that fact that non-tradable goods may be too cheap or expensive when converted at market exchange rates. The purchasing power parity Wikipedia page has some nice example of how this works with the price of an iPad and a Big Mac.
In your case of Russia, because the exports of Russia are mostly oil priced in dollars, even as the exchange rate declines the value of their oil is worth more rubles, and so that should not decline much (except through the falling price of oil which probably is major reason why the ruble declined in the first place). The non-tradable sector similarly wouldn't be fully affected by the depreciation, although in this case through a different mechanism, the PPP correction.