First things first, it's completely common and normal to have a stronger side and a weaker side. Most things we do in everyday life are single-sided. Think about it: When you're walking, you swing one arm forward, the other back, and step one foot forward at a time. When you're driving, you accelerate and brake with one foot (plus, literally the whole car is not symmetrical). When you're eating, you eat with one hand. These are just a few examples of how we do things single-sidedly every day.
Hoomans are not symmetrical beings. And that's okay.
BUT, maybe there's a significant difference between your left and right side, and maybe you want to bridge the gap between the discrepancies. And that's okay, too.
Here are 3 ways to correct muscular imbalances:
1. Unilateral work. You've seen me shout it from rooftops, but here I am again: do some unilateral work. Doing a unilateral exercise means that you're exercising one side at a time. Think: step-ups, lunges, single-arm rows, single-arm presses, etc. It's still important to do bilateral work, like squats, deadlifts, rows, and bench, but understand that doing unilateral work will help you 1, identify which side is a bit stronger/weaker than the other, and 2, hone in on improving the differences.
2. Once you've established which side is stronger/weaker, I recommend starting your single-sided exercises with the weaker side first. This recommendation could be different if you're coming off of an injury -- consult your Physical Therapist for proper instruction. Starting with the weaker side first will allow you to have your sharpest focus and the most energy available for the weaker side. Why start with the stronger side if we're trying to build the mind-to-muscle connection on the weaker side?
3. Another way to improve your strength on your weaker side is to add volume in the form of a an extra set. For example, if your program prescribes 3x8/s, do 3x8 on the stronger side and 4x8 on the weaker side.
If you're not sure which side is stronger or weaker, that's okay. You can still benefit from unilateral training. To start, think about working the bigger muscle groups (glutes, quads, back, chest, and shoulders) both bilaterally and unilaterally throughout your weekly frequency.