What is the meaning of Ello?

Pronunciation spelling of hello.

he

hello

it, neuter third-person subject and disjunctive pronoun (used only to refer to facts, sets of things, and indefinite things that have been mentioned before; generally used with prepositions and rarely used as a subject, except in literary style)

Not used with con; conmigo, contigo, and consigo are used instead, respectively

Like other masculine Spanish words, masculine Spanish pronouns can be used when the gender of the subject is unknown or when the subject is plural and of mixed gender.

Treated as if it were third-person for purposes of conjugation and reflexivity

If le or les precedes lo, la, los, or las in a clause, it is replaced with se (e.g., Se lo dije instead of Le lo dije)

Depending on the implicit gender of the object being referred to

Used primarily in Spain

Used only in rare circumstances

(Freud's concept of) id

Source: wiktionary.org