"Be hep to" is a colloquial term used to describe understanding or being aware of something. If you are looking for synonyms for this phrase, you can consider using expressions such as "clued in," "well-informed," "up-to-date," "aware," "knowledgeable," "in the know," or "cognizant." All of these phrases convey the same general idea of having an understanding of something or being aware of it. Choosing the appropriate synonym will depend on the context and tone of your writing, as some options may be more formal or informal than others.