What is the ruling on a woman publishing an educational video that shows only her hand and voice to teach sewing or explain academic content with the intention of benefiting Muslim women and earning a livelihood?

There is no impediment for a woman to publish beneficial educational videos if she is wearing a complete, শরعي (Islamically lawful) hijab; this is because the voice of a woman is not considered 'awrah (something that must be concealed) according to the majority of scholars. A condition for this permissibility is that she must not speak in a soft or alluring manner, in accordance with the Almighty's saying: "Then do not be soft in speech [to men], lest he in whose heart is disease should covet, but speak with appropriate speech."