The European Parliament is a directly-elected EU body with legislative, supervisory, and budgetary responsibilities. EU voters elect it every five years.
The Parliament acts as a co-legislator, sharing with the Council the power to adopt and amend legislative proposals and to decide on the EU budget. It also supervises the work of the Commission and other EU bodies and cooperates with national parliaments of EU countries to get their input.
The number of Members of the European Parliament (MEPs) for each country is roughly proportionate to its population, but this is by degressive proportionality: no country can have fewer than 6 or more than 96 MEPs and the total number cannot exceed 705 (704 plus the President). MEPs are grouped by political affiliation, not by nationality.