When she was a girl in South Africa's Northern Cape, Katrina Esau stopped speaking her mother tongue, N|uu, after being mocked by other people and told it was an "ugly language."

Now at age 90, she is the last known speaker of N|uu, one of a group of indigenous languages in South Africa that have been all but stamped out by the impacts of colonialism and apartheid.

"We became ashamed when we were young girls, and we stopped speaking the language," Esau told Reuters. Instead she spoke Afrikaans, the language promoted by South Africa's white minority rulers.

Later, as an adult, Esau realized the importance of preserving her mother tongue and founded a school in her home town of Upington to try to pass it on.

N|uu was spoken by one of many hunter-gatherer groups that populated Southern Africa before the arrival of European colonizers. These indigenous people spoke dozens of languages in the San family, many of which have gone extinct.

"During colonialism and apartheid, Ouma Katrina and other (indigenous) groups were not allowed to speak their languages, their languages were frowned upon, and that is how we got to the point where we are with minimal speakers," said Lorato Mokwena, a linguist from South Africa's University of the Western Cape.

"It's important that while Ouma Katrina is around, that we do the best that we can to preserve the language and to document it," she said.

Ouma, or "grandmother" Katrina started teaching N|uu to local children around 2005 and later opened a school with her granddaughter and language activist Claudia Snyman.

But the school property was vandalized during the COVID-19 lockdown, and now lies abandoned.

"I am very concerned. The language isn't where it's supposed to be yet. If Ouma dies, then everything dies," said Snyman, whose dream is to one day open her own school and continue her grandmother's legacy.

"I'll do anything in my power to help her to prevent this language from dying," Snyman said.

Esau has two living sisters but they do not speak N|uu, and she does not know anyone else who does, save the family members and children to whom she has taught some words and phrases.

"I miss speaking to someone," she said. "It doesn't feel good. You talk, you walk, you know … you miss someone who can just sit with you and speak N|uu with you."