As weird as it may seem, I just Googled something like "how to get better at reading". And I found some tips, one of this biggest take-aways for me was to re-read something if you find yourself wandering, and make sure you really understand what you're reading. There have been times I've read several pages, or hell even a chapter, and looked back and realized I was zoned out. The important thing is to recognize this and go back, eventually the focus will come naturally.

I use a Kindle to read and one of my favorite features is the ability to look up a word I don't know. I make sure to do this every time I come across a word I don't know or don't understand given the context. If you don't have this ability, use a dictionary or something of the like.

Also a good tip was reading out loud, or mouthing the words while you read. Hope this helps!

You are reading but you are not concentrating. You brain is going at a much faster rate than your reading speed, which also contributes to the problem. I suffer the same problem.