。
She's planning to visit her uncle in Kyoto next week.
Literal
She [topic-は] Kyoto [attributive-の] uncle [object-を] next-week visit plan is.
京都のおじさん uses の attributively in the 'X-located' sense: 'the uncle who is in Kyoto.' In writing this would more often appear as 叔父 or 伯父, since the kanji distinguish younger and older uncles (叔父 is the parent's younger brother, 伯父 is the older brother) — a kinship distinction English just doesn't make. The hiragana おじさん collapses both, and at the casual level can also just mean 'middle-aged man' (think the friendly neighborhood おじさん). 訪ねる, the verb of choice for visiting people, is distinct from 訪れる (visit a place) and 行く (just go). Closing with 予定です ('have plans to') states the schedule politely.