Help for namespace

See Translating:MediaWiki#Translating_namespace_names: [1]. You should have a local discussion to confirm this though, e.g. at portal talk:mn with a link where other mn.wiki editors will see it.

Thank you. Here discussion begin.

I used "Extended MediaWiki translation". But it doesn't work in our Wikipedia headline. What problem, pls? Can you explain it?

You need to build a consensus agreeing with your proposed change in your discussion. Then you can request the change here on support. Because you are requesting a change to a namespace name, using SpecialTranslate won't work.