Karuta i

i
い, hiragana
イ, katakana

石の上にも三年

Ishino uenimo san-nen 

My dictionary said it means, 
'Patient men (will) win the day. ' 
'Perseverance will win in the end. '

I found this direct translation and the explanation on the Internet.

[Direct translation]
Three years on a (cold) stone (will make the stone warm) .

[Explanation]
In Japan, we have an idiom that says that three years on a cold stone will make the stone warm. What it means is that you should not give up, and that perseverance and patience will bring good results. Don't give up !

  [Words]

石の上  on a stone

三年  three years