The phrase "hard to understand" can be replaced by a range of synonyms that convey the same meaning. These can include phrases like difficult to comprehend, puzzling, confusing, perplexing, impenetrable, incomprehensible, bewildering, and abstruse. Each of these terms describes a situation where information or language is challenging to grasp, interpret, or decipher. Students struggling to understand difficult concepts or phrases in textbooks or lectures may find these synonyms particularly helpful in describing their experiences. Similarly, writers, speakers, and educators can use these synonyms to describe complex ideas that may be challenging for their audience to follow or comprehend.