Wikimedia talk:Template messages

What in the world is this???

tympanic membrane

https://my.clevelandclinic.org/health/body/24642-tympanic-membrane-eardrum

Cell[BoxData[RowBox[{"Sequence", "[", RowBox[{TagBox[FrameBox[SubscriptBox["expr", "1"]], "Placeholder"], ",", TagBox[FrameBox[SubscriptBox["expr", "2"]], "Placeholder"], ",", TagBox[FrameBox["…"], "Placeholder"]}], "]"}]], "Input", CellTags -> "Sequence_templates"]

Kinda need some help. And YES I know I can get in trouble asking what this is.. It's because I CARE.

JUST TELL ME WHAT THIS IS?? PLEASE!! THANK YOU!! SOS.