Here is a great write up explain what the cryptic symbols mean.
https://medium.com/@codenameyau/step-by-step-breakdown-of-dev-null-a0f516f53158
Combine this with command -v to bypass “normal function lookup” from https://askubuntu.com/questions/512770/what-is-use-of-command-command we can use this to check if certain applications exist.