Like many countries, Japan uses a 12-month calendar. The names are very simple. January is literally “Month One”, February is “Month Two”, etc:
一月 = January
二月 = February
However, before the Meiji Restoration (mid-1800s) it was common to use an older 12-month system. These months’ names referenced the weather and the seasons (similar to the French Revolutionary calendar).
In this older calendar, February is 如月.
Japanese learners will recognise the kanji 月 as “moon” or “month”.
The first kanji is not common these days. It can be substituted with 衣更, which has the same sound and gives clues as to the original meaning of the month.
衣 = clothing
更 = more and more, further
This 更 refers to a continuing demand for something. So February is the month when it is still cold so you still need all your warm winter clothes.