In our current reality, with online learning, one of the best things you can do to help your student is to encourage him to read. Your child should not only be reading what her teacher assigns, but should be reading independently.
Encourage your child to read fiction and nonfiction texts--books, magazines, newspapers. The more your child reads, the better reader he will become. The more your child reads, the more things she will learn. Being a better reader and having more knowledge will help your child succeed in all classes and will help your child do better on standarized tests.
Your student can check out books from the school libraries. Reach out to the library assistant at your child's building to learn how. Also, you can check out books from the public library. Contact the librarian at your local library to find out more about the process. Don't forget about ebooks as an option.
Another thing you should encourage your student to do is write. Writing daily, like reading daily, will help your child improve his skills. Provide your child with a journal or composition book and different kinds of writing tools to make writing more enjoyable for her. Stickers and pens or markers in a rainbow of colors can make writing fun. These are items you can find at the dollar store.
The best thing you can do for your student is to model reading and writing yourself. If your child sees you reading and writing, he is more likely to read and write, too. Reading and writing along with your child will show her these things are enjoyable, relaxing activities and will encourage your child to read and write independently.