John 15:1 "I am the true vine, and my Father is the vinedresser."
The words are in red, so this is Jesus talking. So Jesus is the True Vine and God, His Father, is the vinedresser or gardener.
15:2 "...every branch that does bear fruit He[God] prunes, that it bear more fruit."
Pruning sounds painful, doesn't it? When you look at a tree getting pruned, it looks like the gardener is hurting the tree. In reality, it helps keep the tree healthy. Say a small peach tree has grown a bunch of new branches. The tree is putting all its nutrients towards those new branches and less towards fruit. Now a good gardener will see this and prune off some off the new branches. In doing so, he helps the tree focus more off its nutrients on the fruit than new growth.
What Jesus is talking about here is like that in a way, but 'pruning' for us isn't cutting off a limb(thank goodness!!) its trials.
When God sends trials our way, where the Bible says 'that it may bear more fruit', pruning makes the tree stronger. For us, the trials make us stronger and hopefully closer to God.
Trials come to everyone, whether they are small things or hard trials. I have had a little bit of both, small 'branches' and a little more developed 'branches' pruned off. It hurts, it almost always does. Even then though, I knew God was with me. I grew closer to Him. They strengthened my relationship with Him.
That is why God sends trials to us. To help us grow closer to Him. Its not because He doesn't love us, its the opposite. He doesn't want us turning to other things when we hurt. He wants our attention always focused on Him, no matter what.
