How can I know what is the direction of clockwise or counter-clockwise? I mean, from which perspective do I have to see a fan to see the direction of rotation?

I once had a person ask me about turning a screw "was clockwise from outside the clock looking in or inside the clock looking out?"  My response was that if they could get inside the clock they could turn the screw any way they wanted to.

Each blade on a fan has a leading edge and a trailing edge.  The leading edge is the direction of rotation, doesn't make any difference which side of the fan you are standing on.

Post a picture. the shape of the blade, the direction of flow, and perspective are needed to answer your question, based on the type of fan.

I believe Javier is asking about the rotation that the user specifies in the rotating reference frame. The direction that your body will rotate always seems arbitrary to me, it probably has to do with the direction of the base plane that you generated the part from. There is a way for you to easily see the direction of rotation though, when you are in the rotating frame of reference dialog there should be a highlighted green vector and moment in the assembly, like so:

If you want the other direction, just reverse the sign on the magnitude of your angular velocity.