Belarus is a Russian-speaking country located between Poland and Russia. Like any county in that part of Europe, it has an interesting history, including wars and invasions. The majority identify with Slavic Orthodox churches, and recently the government restricted Pentecostal Christians. The instructions are clear ‘Do not pray in tongues! Only pray in Russian!’
I’m not sure how the authorities will enforce this, and it’s not clear why they need this rule. People who pray in Pentecostal churches are usually harmless. Where I live, they are a good influence in the community.