This stretch focuses on the chest (pecs), front of the shoulder, and can be used as a bicep stretch with a small modification. Stand near a wall and place the hand of the arm you want to stretch against the wall a little below shoulder level, with your fingers pointing backwards.
With your hand secured against the wall, rotate your torso forward (away from the wall). For example, if you are stretching your left arm, you rotate your body to the right. Make an effort to keep your shoulder down and relaxed during the stretch and find the position that stretches your chest the most.
You can move your hand a higher or lower if it gives you a better stretch, but don’t move the hand so high that it forces your shoulder to shrug/move towards your ear. It’s also important to keep a small to moderate amount of bend in the elbow, otherwise there will be too much stress on the elbow joint.
In order to make this more of a bicep stretch, position your hand so your fingers are pointing up or you can place your knuckles against the wall with your thumb pointing forward. The straighter your arm (without being locked), the more this will stretch the bicep. However, this position usually decreases the stretch of the chest, so use whatever version(s) target your tight muscles.