If something is unremarkable, there is nothing about it worth pointing at. It is not bad — that is the part students miss. It is just ordinary enough that you would not stop and say anything about it. A town can be unremarkable: clean, fine, nothing to see. A meal can be unremarkable: you ate it, it was food. A person's face, a school report, a Tuesday. The word carries a small cool distance. When a reviewer calls a film unremarkable, they are being politer than "bad" but they are not being kind either — they mean it left no mark, and forgettable is worse than hated in that world. Between friends people would just say "nothing special" or "it was okay". Unremarkable is the written, slightly formal version. It has one more use worth knowing, because it looks strange the first time: in medicine, "the scan was unremarkable" is good news. It means the doctor looked and found nothing to remark on — nothing wrong. So in a hospital report, unremarkable is the word you want to hear. Also note it usually goes with things and situations rather than with people's character. You would not normally call your friend an unremarkable person to their face; that lands as an insult even though the word itself is mild.