I'm in 7th grade and I need to gain more vocabulary for the SSAT next month. Is there any good?

Watch a book for a while. A dictionary is a popular choice. Yes, lots of people read the dictionary.

Get novels. They are free at the local library and some of them are really good stories, no matter what you consider "really good". Keep a notebook and record the figures of speech and literary devices as you notice them. Quite often someone will ask where you got some remark, and it is nice to have that information in your notes.

Instead of looking at one word at a time, look at two words. That forces you to stop talking to yourself, so you are no longer limited to reading as fast as you can talk. You probably talk about 100 words per minute (WPM). The average college graduate reads 300 WPM. Just by looking at two words at a time you can double your reading speed. Then by looking at a whole line at a time you can read much faster. The big benefit is that your memory expands along with your reading speed so you can remember the large volume of information you are taking in. With a little practice it is possible to read an entire page in two seconds with near total recall of the information on it.