This puzzle utilizes the classic internet text obfuscation technique 13375p34k, or leetspeak, to hide letters as similar-appearing symbols. For example, in the first line, 7 |-| 3 /\/ | /\/ 7 |-| 1 3 7 7 3 |2 may be read as THE NINTH LETTER. The full translation is as follows:
THE NINTH LETTER
LETTER 5
SYMBOL 1
NEXT TO LAST
THE FIRST SYMBOL
THIRD LETTER
THIRD SYMBOL
THE 4TH SYMBOL
THIRD FROM LAST
SYMBOL THREE
SEVENTH SYMBOL
THE TENTH SYMBOL
SECOND SYMBOL
From here, the next step is to let each line refer to itself. Using the first row again, the ninth letter of 7 |-| 3 /\/ | /\/ 7 |-| 1 3 7 7 3 |2 is 1, representing L. Some solvers reported that it was more intuitive for them to write the strings in plaintext first, which works as well for the lines which refer to letters. However, when the clue refers to symbols, it is necessary to use the untranslated 13375p34k line. (Lines which don’t specify letters or symbols are the same either way.)
Continuing this process, we end up with the phrase 1 3 5 5 7 |-| 4 /\/ 3, or LESS THAN THREE. Writing this as symbols yields <3, which is a common symbolic representation of a HEART.