Guitar String tension affects how easy the guitar string feels to you fingers when you play. Guitar scale length as well as gauge size will both affect the amount of tension that the guitar string will have. Larger gauge guitar strings have more tension than smaller gauge guitar strings. There are advantages to both. Some players prefer larger gauge guitar strings because they can produce more volume and if they are heavy pickers, larger gauge strings can reduce string buzzing. However, larger gauge guitar strings take a lot of effort to play and it usually takes a player a good deal of playing experience to build up their finger strength for this. Lighter gauge guitar strings are easier to play.
There are other things that can make a guitar string easier to play as well. Making sure the action on your guitar is set up correctly for the way you play is very important. The action is the distance from the fret board to the string.