You learn to use your wit to supernaturally distract, confuse, and otherwise sap the confidence and competence of others. When a creature that you can see within 60 feet of yourself makes a damage roll or succeeds on an ability check or attack roll, you can take a Reaction to expend one use of your Bardic Inspiration; roll your Bardic Inspiration die, and subtract the number rolled from the creature’s roll, reducing the damage or potentially turning the success into a failure.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.