Bash (Bourne Again SHell) is the default shell on your mac. You use it when you open Terminal and execute commands. It has two associated files for customization, .bash_profile and .bashrc
You can teach your shell to alias to other commands. For example, here are the aliases I use
alias g='git'
alias gp='git push'
alias rpy='pry'
alias rials='rails'
Open up your .zshrc or .bashrc and add your aliases.