This is the 7728th most frequent Japanese word.
叔父
"Uncle" (younger brother of one's parent).
Here, '叔父' refers to the speaker's male uncle who is younger than their father. It demonstrates familial relations.
私の叔父はとても親切な人です。
My uncle is a very kind person.
In this context, '叔父' is explicitly defined as the mother's younger brother, indicating the relationship.
母の弟、つまり私の叔父が旅行中です。
My mother's younger brother, that is, my uncle, is traveling.
The term '叔父' here again refers to the male sibling of the speaker's parent who is younger, used to show respect and gratitude.