Tomato-based pasta sauces are pretty much made of a combination of tomato paste, tomato puree, diced tomato, oil, and salt.
Depending on what it’s marketed for, other vegetables, herbs and spices may also be added.
For example, “chunky pasta sauce” may contain carrot and onion. “Bolognese with mushroom” will have mushrooms, and “Bolognese with red wine” actually does have some red wine in there.
Unfortunately, when these jars are labelled “Bolognese”, they do not contain minced meat like traditional Bolognese. What it probably means is that they are flavoured to accommodate a Bolognese sauce. You would have to add your own minced meat in the cooking process if you wanted a true Bolognese.
Certain brands may add thickeners or sugar, which makes the sauce a more appealing consistency and reduces tartness, respectively.