What is the meaning of Ellos?

they

they (third-person plural masculine pronoun)

they (masculine or mixed group)

third-person singular imperative of eallit

plural of él (“they, them”)

Like other masculine words, masculine 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).

Used primarily in Spain.

Only used in certain circumstances and rarely as a subject pronoun.

Source: wiktionary.org