In scrum, we divide our work into iterations or cycles which are called sprints. The output of the sprint should add some value to the customer. For every sprint, we talk about time-boxing, which means it will have a start date and an end date. This timeboxing ALLOWS the customer to KNOW when they can expect the output from the TEAMS, ALSO the team knows how much they can commit so as to deliver a quality item to the client. 

Time-boxing also allows the team to focus on the value, whatever they pull as commitment is expected to be the highest priority item from the backlog which will add the highest value. Protecting a sprint means, the scrum master will make sure that the team does not commit more than their capacity, else, they won’t be able to complete the work in time. Protecting a sprint also refers to ensuring the stakeholders are not over-doing the participation in the daily activities, as it impacts the team’s focus. The team can set some ground rules or can have working agreements to make sure they strike a balance in the scrum ceremonies. And LASTLY, protection is also in terms of shielding from outside interferences.