expert on

In Italian, 'esperto di' is used to describe someone who has a high level of knowledge or skill in a particular area or subject. It can be applied in various contexts, such as professions, hobbies, or specialized fields. For example, you might say 'è un esperto di tecnologia' which means 'he is an expert on technology.' The phrase is typically used to convey respect for someone's abilities and understanding in their area of expertise.