Football / Soccer / Calcio / Futebol / Fußball

Ok, I recently got into soccer/football and there is something that is confusing next how does the European leagues works. I tried reading up on it but only got more confused.

For example, I know there is La Liga and Premier League, but do they compete each against each other for a championship like the NBA? Like does Barcelona compete against manchester(I know I might sound like an idiot, but I’m really tryna understand).

Do La Liga teams only compete against other Spanish teams?

Explain to me like I’m an idiot because I am when it comes to soccer 😂 I am American