Most shells let you do some arbitrary work before/during the display of the prompt line (in Bash, you can use `PS1` and `PROMPT_COMMAND`). Some people then install special fonts that let them render these fancy “bar segment” things. [Powerline](https://github.com/powerline/powerline) is a notable package for this, but there’s a lot of simpler alternatives out there nowadays.
It was only mentioned twice, and in two paragraphs in the whole article. It established the motivation for his experiment. You might draw from different motivations for trying TaskRabbit.