After the third move e6, if white does not move d4 and moves e5, the what can black do because his kingside knight is blocked?

So thats its name.

I know black is preventing the invasion of white's knight, but I see a position advantage for white.

Looks more like the Scicilian Dutch variation.

@sonty: After white plays 3. e5 you can easy equalize with 3. ... d5 The game often transposes to a line in the french defence which is considered harmless for black: 1. e4 e6 2. d4 d5 3. e5

it doesnt seem to be doing anything at that time because  it doesnt stop what white is trying to do

I think a6 is a very good move.