aquello
that
aquel
that
+
-lo
neuter suffix
Aquello means that and is formed from aquel0 (that0) + -lo1 (neuter suffix1), making it the neuter form of 'that'.
pronoun
  1. that
    That (thing or idea) over there, far from both the speaker and the listener
    ¿Qué es aquello en la distancia? // What is that thing in the distance?