This is a recurring pro-Kremlin narrative questioning the EU institutions' legitimacy and powers and seeking to discourage voter turnout in elections.
The European Parliament is the EU's only directly-elected institution. Since 1979, it has been elected by EU voters every 5 years. The last elections were in May 2014, and the next ones are in May 2019.
The European Parliament is one of the EU's two law-making bodies. It has constitutional-type and ratification powers. It passes EU laws, together with the Council of the EU, based on European Commission proposals. It has budgetary powers, scrutiny over the executive, hears citizens’ petitions, and appoints the European Ombudsman. A detailed overview of the European Parliament’s role in the European decision-making process can be consulted here.