It says "My brothers and sisters, you will face all kinds of trouble. When you do, think of it as pure joy. Your faith will be tested. You know that when this happens it will produce in you the strength to continue. And you must allow this strength to finish its work. Then you will be all you should be. You will have everything you need."
Wow! What does that mean?
When you have trouble or something bad is happening to you, you should try to be happy about it because you just want to know that it is a test for your faith.
When trouble has come and you consider that joy, you have to know that God has given you strength to get through it.
When trouble comes to me I will do that.
When your faith is tested it makes you strong. If you keep being strong then you will be who God wants you to be and have all that you need.