Venezuela is a country that exports (or sells to other countries) a lot of oil.
Because it has one of the largest oil reserves in the world, it focuses on the production of oil as one of its main exports. In the past when oil prices were high, having only one main export was not a problem — the country made plenty of money to purchase things from other countries that they did not produce or produced very little of themselves.
Recently, however, oil prices have dropped A LOT. The same amount of oil that Venezuela exports today, brings in much less money into the country. What’s the result? Venezuela is unable to pay for as many things as they used to buy from other countries. This has led to long lines of people at grocery stores hoping to buy things like sugar, our, and even toilet paper, before they are turned away because supplies have run out.