What is the meaning of あれ?

distal demonstrative, something far off removed from both speaker and listener: that, yon

(deictically) that one over there (far from the speaker and the addressee)

(anaphorically) that one we both know (both the speaker and the addressee know)

third-person personal pronoun: he, she, that person

you-know-what; a thing whose name the speaker does not want to mention

  1. sex
  2. cockroach

sex

cockroach

second-person pronoun: you

あれ, アレ: "you know what I mean"

huh? (expression of surprise and confusion when talking to yourself)

first-person personal pronoun: I, me

imperative of あり (ari, to exist); imperative of ある (aru, to exist)

Source: wiktionary.org