。
In the north, there are huge mountains.
Literal
North-region [in-には] giant mountains exist.
北部 ('the north, the northern part') is a compact compound. 巨大 ('huge, giant') is a na-adjective used attributively as 巨大な. 山々 is a reduplicated plural — the 々 marks repetition of the preceding kanji, emphasizing plurality ('mountains, many mountains'). Reduplication is a distinct Japanese plural marker.