Just wanted to know which european leagues have relegation and promotion playoffs.
I heard it's fun and intersting ;)

Almost all the second tiers.

MLS has it as well, but obviously that's not European.

But, which leagues specifically?

Bundesliga 3rd team from the bottom vs. Bundesliga 2 3rd team from the top. (Ligue 1 & 2 got same)
Championship, Serie B and many others.

Intersting...
So,
La liga, Premier league and Serie A playoffs is only in second division.

My english is weak? :)

That happened once in Super Lig, back in 2011-2012 season. The last game of the play-off round was Fenerbahçe-Galatasaray. A win was enough for Fenerbahçe to become the champions, otherwise Galasataray was going to be the champions.
The game ended 0-0 and Galatasaray won the league at Fenerbahçe's stadium. You can imagine the rest, then the play-offs never have been played again in Super Lig.

@EduardoZ Don't worry too much about your english, we mostly understand what you mean. ;)

Thanks mate ;)
You are a cool guy