Quegli is a third-person demonstrative pronoun used to refer to persons who are far from the speaker, either in time or space (or both).
It functions most of the time as the subject of a verb in the sentence and is used in the singular masculine form only.
In old literary texts you can also find its older variants quelli and quei. For example:
Quegli non vuole vederti più / That person doesn’t want to see you anymore
DO NOT MISTAKE the demonstrative pronoun quegli (third-person masculine singular) with the demonstrative adjective quegli (masculine plural form of quello).
Examples:
masc. sing. pronoun —> Quegli non ne vuol più sapere di te / He (that person) doesn’t want to
deal with you anymore
masc. plur. adjective (quello) —> Mi ricorderò sempre quegli strani palazzi di fronte alla mia
finestra / I will always remember those strange buildings in front of my window
