This is the 222nd most frequent Romanian word.
acestuia
"Acestuia" means "of this (one)" (genitive/dative singular, masculine or neuter).
Here, 'acestuia' refers to a person whose words were listened to, functioning possessively.
Am ascultat cu atenție cuvintele acestuia.
I listened carefully to his words.
In this case, 'acestuia' emphasizes the subject's relevance and contribution.
Importanța acestuia pentru proiect este evidentă.
His importance for the project is evident.
This usage showcases 'acestuia' as indicating ownership of an opinion to a subject.