Most jurisdictions allow for deferrals and excusals from jury duty. You usually can't be excused from jury duty because of your employment status. You may be able to be deferred from a particular reporting day because of work requirements, but generally not excused completely.
When you are called, you'll report to the location specified at the time specified. You may then be put in to a jury pool -- a group of a few dozen to a couple hundred people. You'll meet the judge and the lawyers for both sides. They'll explain what the case is about, talk about how long it will take.
Minor hardships or inconveniences to an employer are not legal reasons to be excused from jury service. However, you may request to be postponed to a more convenient time. If serving on jury duty will create an extreme financial hardship, visit the online Juror Portal to request an excuse.
You may be excused if you have a serious health problem. If you are sick or injured, you may postpone your service or request an excuse. If you are disabled, you may request a permanent medical excuse. Follow the directions on the summons for postponement or excuse.