Meaning that it is OK to get angry. Their are reasons, justifiable and righteous reasons, to be angry. We just don't want to hold on to those feelings. Holding on to anger can literally destroy the quality of our lives and we don't want that!
We also don't want to act out because of anger. All kinds of mistakes and life damaging results come from acting out when we are angry. Many people have experienced the suffering that comes from anger: Job loss, ruined relationships, divorce, depression, jail, homelessness, war, violence, bitterness, being demoted, loneliness, and more!
Also, please remember that if you sin because of your anger and put a stumbling block (mess with their day) in the way of another person, then you need to make sure you repent by telling them you are sorry and fixing what you can right away, because you might not see that person again (nobody is guaranteed tomorrow) and that 1 sin can cause you to have your name blotted out the book of Life (lose salvation - and yes you can lose it).
When you don't correct something then satan enjoys being the tattletale and runs to God with "look they refused to make something right - they listened to me and stayed angry!" and he makes sure that he reminds you of your mistakes over and over again, so that he can get you to beat yourself up with the guilt stick continually.
Since the sun is only in the sky for a set amount of time each day, God is letting you know that you need to feel a sense of urgency to make things right as quickly as possible. When you correct something that was wrong you make God proud of you, and he remembers the sin no more.
What a great example of Forgiveness and Mercy!
Enjoy this gift of 30 days of breaking open scriptures.
~ Miss J