I just bought a 3030 336 whats a good scope for it? What is a red dot scope.

Might want to specify a budget first, because the sky is the limit.

A Nikon Prostaff 2x7 power for around $120's, a Bushnell 3200 in 2x7 for about $225ish of a Burris Fullfield II in 2x7 for around $160.
A red dot is a small scope like device that projects an "image" or dot of some sort and color that you put on target and shoot.