Language selector when, how or make yourself?

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Hi Guys,
Buenos días,
Bonjour,
…
How to add my multi language selector?
How to push to the nav bar with no extra cost (yes, I will pay CSS but later)?
Hint or Choice as language selector, I my G…!

Some best solutions,

Regards

2

In my App, I use one column by language.
and a next one this “IF THEN ELSE”
If lang=FR the descr_FR …

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