The president is the executive alongside the ministers. The opposition is the other parties that have an opposite view on things.

In a presidential system the president’s party is the government and the other parties are the opposition. Doesn’t matter how many seats in parliament anyone has.

The opposition is whoever is not in power. Anyone complaining about being locked out is clearly not in power, making them the de facto oppposition party regardless of official labels.

> point still stands, if you control the parliament, aren’t you the majority and the other side is the opposition?

In a parliamentary democracy, the governing coalition and opposition are clearly delineated. In a presidential system, a legislature controlled by a party different from the president tends to be referred to as an opposition legislature, e.g. the House is currently in opposition to Biden.