1A counter for months, read かげつ, used for spans of time — 一ヶ月 'one month', 三ヶ月 'three months', 半年(六ヶ月) 'half a year (six months)'. The character ヶ is a small katakana ケ derived from the kanji 箇; the same counter is also written か月, カ月, ヵ月, or 箇月. Newspapers and textbooks often prefer か月 or カ月, while ヶ月 is most common in everyday writing. Pronunciation shows sokuon with some numbers: 一ヶ月 (ikkagetsu), 六ヶ月 (rokkagetsu), 八ヶ月 (hakkagetsu / hachikagetsu), 十ヶ月 (jukkagetsu / jikkagetsu).
日本に来てから、もう三ヶ月が経ちました。
It's already been three months since I came to Japan.
あと二ヶ月で大学を卒業します。
I'll graduate from university in two months.
赤ちゃんは生後六ヶ月ごろから離乳食を始める。
Babies typically start solid food around six months old.
この本を読み終わるのに一ヶ月もかかってしまった。
It ended up taking me a whole month to finish this book.
新しい仕事は最初の三か月が試用期間となっている。
The new job has a three-month probation period at the start.