Once every 5 days there is a vote to elect the leader of the Nation (presidential) and another to assign the seats of Parliament (parliamentary).
Depending on the form of government we find different #elecciones:
In Republic there are presidential elections (elect the leader of the Nation) and parliamentarians (vote to the party to get seats).
In monarchy there are parliamentary elections but Parliament is not so important. In dictatorship there are no elections of any kind.
To vote you need to have the residency in a region of the nation and carry at least 24h with residence in that country. When are the elections you will have a notice in the general profile:
Election of leader: presidential elections. Elections have begun: vote: parliamentary elections.
Select the blue button and choose the party or candidate you want to vote for.
It is not possible to rectify your vote, so make sure you don't go wrong. The voting counters show you the time remaining until the end of the vote. Sometimes there is a second counter that tells you when you can vote (you need to have the 24h residency in the region before you can vote).