Trans-2-betene indicates that the C=C double bond is between the 2nd & 3rd C atoms. This creates a more-or-less planer structure surrounding the C=C with a H atom and a -CH3 group on each carbon. The "trans' indicates that the -CH3 groups are on opposite sides of the C=C bond (as opposed to -cis where they would be on the same side of the C=C bond.) The trans- isomer would be nonpolar but the cis- isomer would be somewhat polar.
