Fetching details from the dictionary...

the Rat (first sign of the Chinese zodiac)
「子」 has other readings with different meanings.
干支で今年は子の年だそうですね。
This year is the Year of the Rat.
子は十二支の最初の動物です。
The Rat is the first of the zodiac.
彼は干支で子年生まれだそうです。
He was born in the Year of the Rat.