It is not always wind 
it depends even on the stream
that is whether you are going upstream or you are going downstream.
if you are going downstream and the wind is from behind it is easy to row the boat
But u have to give expalantion also
Yes, It is easier to row a boat if there is wind coming from back because it applies force on the sail and it moves forward. The opposite happens if the wind is coming from the front side. Your speed will slow down in that case.
Hope this helps you..! ^_^