Can I skip my dinner, instead of having it at 7 PM or having a light dinner?

It depends on your hunger. If you do NOT feel a genuine sense of hunger in the evening, it is alright to skip dinner. 

However, if you feel keen hunger, then skipping dinner is not the best option. The hunger must be satiated with pure, easy-to-digest, Satvic foods. We must listen to the needs of our body, and cause no violence to it.