At gym doing ab machine and got extreme head pounding and the whites in my eyes turned red. what's that mean, the eye part exactly thank you!

Increased pressure: You are increasing the abdominal pressure therefore blood "backs up" into the vascular system in your eyes.

Hemorrhage: If the vision is ok, then you have probably leaked a little blood from the veins over the whites of your eyes. This is benign and will go away in 4-10 days. However if the vision is disturbed, or the eyes are painful, then you should see an ophthalmologist right away.