I'm slow, i am like the dumb one that doesn't understand things. i need to think faster and better vocabulary?

When you read, try to picture what's being explained in your mind. And yes, you should look up a word if you don't know it and can't figure it out using context (finding the definition based on how it is used in the sentence). Not every single word in a sentence is of high importance, don't dwell on articles, they are just there to guide you. Focus on descriptive words and actions, and give faces to the characters in the books you read. Also, try to give them a voice and imagine the scenery. All of this helps you focus and increases your creativity.