The ad is designed to be uplifting, inspiring, aspirational.
It's meant to give the audience a feeling of courage and determination, which makes it more likely they will play a sport and buy Nike gear.
How does it work?
Nike ads are often about extreme contrasts.
We have a young Black girl in a pretty dress which gives a sense of innocence, vulnerability, and beginnings.
BUT she is captured in a strong, dynamic pose and presented in dark monochrome with stark, white, simple text, which gives a sense of dignity, strength, and resolve.
Combine those two emotions and you get the courage and determination to undertake a lifelong mission.
(Especially if you recognise the girl as tennis legend, Serena Williams.)