Growth towards is growth reaching a goal or growth in an area. Here the number of low skill jobs is growing, as well as the high skill ones. So the middle class jobs are hollowing out, or emptying. There is growth on both sides, but none in the middle, so that the middle is disappearing.

"Towards" is used together with "growth", so it would be "the growth of (something) is in this direction". It says that low skill jobs are increasing, but also that other areas are not growing, or growing less than low skill jobs. Literally,, "hollowing out" means that you take out the centre of something. For example, hollowing out a watermelon, you leave only the outer shell but not the inside. In context, it means that the middle class is getting smaller, that there is less of the middle class. You can use "towards" in many ways. For example, "she walked towards me" means someone is walking in my direction, closer to me. "She tends towards apples" means that she likes apples (more than something else, or as opposed to something else). "Towards" when not used literally, has a meaning of [this] instead of [something else].

towards means direction(prepostion) or in progress(adjetive) to use it in the direction sense "Im moving towards the house" or in the sense of progress "I have something that i need to move towards" they both mean straight ahead or forward in a sense of speaking hollow - mean to remove the inside of something