What does it mean to have something highlighted in red in sublime text? [closed]

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I’m not sure why the start of my note is highlighted in red. In the screen shot shown above “Font Awesome” is just meant to be a note. however < is highlighted in red and rather than being white, the whole note is purple. This is a copied and pasted code but I also attempted to enter it in by hand and the same thing still happens. I’m still pretty new to the coding world but in the month or so that I’ve been dabbling, I have never seen this red highlighted item. Could anyone possibly tell me what it means? Does it matter if it is there, and if so, how to I remove it?