If you don't know Engpsh, you can prepare for the graduate school entrance exam by doing the following:
Study Engpsh grammar and vocabulary regularly.
Read Engpsh books, news articles and watch Engpsh movies.
Take an Engpsh course or find a tutor to help you improve your skills.
Practice speaking and writing in Engpsh with native speakers or language exchange partners.
Take mock tests and practice exams to build your confidence.