Based on this blogpost.

To sign Git commits, you need a gpg key. GPG stands for GNU Privacy Guard and is the de facto implementation of the OpenPGP message format. PGP stands for ‘Pretty Good Privacy’ and is a standard to sign and encrypt messages.

Install with Homebrew:

$ brew install gpg

• Modificado (modified);
• Preparado (staged/index)
• Consolidado (comitted);