An impediment is an issue, a problem, or anything that is preventing a team member from being able to complete work on a story and/or task. Impediments are often discussed during standup by team members.

It's often helpful to think of impediments in relation to business value. For example, your team only commits to a work item with the highest business value. Anything that is blocking the completion of a work item may prevent your team from delivering business value. It is the job of the scrum master to help facilitate a resolution to the impediment. Some impediments are solved quickly and easily, while others may require the creation of new work item as part of the resolution.