The GIRM is the General Instruction of the Roman Missal. In some traditions, this type of General Instruction is also known as General Rubrics.
Properly defined, Rubrics are those words and sentences printed in service books that give instruction on the conduct of the service. The name Rubric comes from the latin word for Red, because historically, rubrics were always printed in red ink.
In most leaflet missalettes, rubrics are in smaller, italic type while spoken parts in a slightly larger, regular type.
If you are curious just to see what they look like, ask your parish priest to see a copy of the Sacramentary. The red ‘stage directions’ as they are sometimes called are the rubrics.
Rob+