It looks like you wanted to buy wrist straps and instead bought wrist wraps. At least, those are the English terms I'm familiar with and they still get misused.
It's still a useful product. Wrist wraps are used to keep your wrist from bending during pressing movements: exercises like bench press or overhead press. YourSome lifters use them during squats to keep their wrists straight too. You slip your thumb through that small ring, wrap it around your wrist, and then velcro it closed. You can leave the ring around your thumb on or off after based on your preference. Exercises like bench press or overhead press. Some lifters use them during squats to keep their wrists straight too.
Unfortunately, it won't have much effect on your grip for deadlift or pull-ups.