The Army Physical Fitness Test (APFT) is required of all Active Army, Army National Guard, and Army Reserve soldiers. It consists of three fitness events. This test is a simple way of measuring a soldier's major muscle groups' endurance and ability to move the body, as well as the performance of the soldier's cardiorespiratory fitness. The lowest passing APFT standards reflect the minimum acceptable physical fitness level for all soldiers, regardless of MOS or component. Soldiers with permanent profiles or temporary profiles of greater duration than three months may take alternate APFT events.
The US Army is in the process of reevaluating the physical fitness test and may actually create two versions - Army Physical Readiness Test (APRT) and Army Combat Readiness Test (ACRT). You can read more on this page about the new tests and what locations are currently trying the new tests. In the fall of 2012, the Army decided that further studies were needed to verify that the proposed new programs would actually increase the physical readiness of recruits and more testing was ordered.
Just before you take the APFT, you will have your height and weight measured. You can read more about those standards here. You might also want to download and review the US Army Pocket PT Guide to help prepare for enlisting.