Taro cake is similar to turnip cake 蘿蔔糕 (lò baahk gōu) but made with taro mixed with rice flour and tidbits like Chinese sausage. It's cut into squares and steamed or pan-fried.
Taro cake is sometimes known as yam cake in Malaysia and Singapore, but it's not yam as in sweet potatoes, it's really taro.
芋頭 is taro, and 糕 is cake, so 芋頭糕 is taro cake.