I wish there was a good video on this in English. I'll try to find one later.
International Mother Language Day has been being observed since 2000[4] to promote peace and multilingualism. The date corresponds to the day in 1952 when students from the University of Dhaka, Jagannath University and Dhaka Medical College, demonstrating for the recognition of Bangla as one of the two national languages of East Pakistan, were shot dead by police near the Dhaka High Court in the capital of present-day Bangladesh.
"Mother language" is the calque of a term used in several Romance languages: lengua materna (Spanish), lingua madre (Italian) and langue maternelle (French). A more fluent English translation would be "mother tongue", although "native language" is the most comprehensible term in English. In linguistics, "mother language" refers to an ancestral (or proto-language) of a language family.
>inb4 designated haha