Arms are one of the better known muscle groups. It consists of forearms, biceps, and triceps. Each of these also have multiple muscles within them, but that is not the most important to know when starting.
Abdominal muscles are the "core" of your body so they are also called your core. These muscles are in your abdomen and help with stabilizing your spine and bending at the waist.
Your chest is not always seen as an important part of your body, but it is extremely important in lifting strength. You need your chest to rotate and extend your arms.
Legs are another muscle group that are well known. They consist of many muscles, but the main groupings are quadriceps, hamstrings, and calves. These are the main muscles driving the movement of your body.
The back consists of many muscles like your lats, traps, and delts. Each of these has multiple parts as well. Strengthening these muscles can help with back pain and keep your body straight.
Finally, shoulders have eight muscles that attach your body to your arm. Some of these in your shoulder are also in your back or arm exercises, like triceps or delts.