Three angle brackets. <What does it mean? what should I do?

Three angle brackets (& lt;) are the meanings of the following brackets: & lt; ADMIN_OPTION and ADMIN_OPTION & lt; & lt; ENTRY_DISPLAY and ENTRY_DISPLAY look a little annotated, and they don't feel like comments. Can anyone explain this? Thank you. Three angle brackets. <What does it mean?
As shown in the following figure, < It seems like a comment. Can someone explain it? Thank you. The meaning of the HTML structure should be guaranteed. Thank you.
$ Entry_display. = <

Add a New Entry

ADMIN_OPTION;
///////////////////////////////
$ Entry_display. = <


$ Title

$ Bodytext

ENTRY_DISPLAY;

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The meaning of the code segment!
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PHP code

$ Somevar = <