Pallof presses are a great exercise to increase trunk stability. Using a resistance band makes for easy set up and adjustments. You can modify the movement by changing your body position in relation to the band. Here (video below) is an example of standing, kneeling, and a half seated Pallof Press
When preforming the movement, you should feel your internal and external obliques contract opposite the resistance band. Getting into a half squat position really hits the obliques. Weak obliques usually mean weak adductors and this exercise is a way to improve strength in this area as well. The pressing action varies the stresses placed on the core which is nice to simulate real life movements.
The core isn’t a prime mover so don’t train it like one! Trying different exercises that help to mimic functional movements will help you feel better on a day to day basis!