We make a will to express our wishes for our possessions when we die, so God's will is what He wishes to be done. God's will include His commands and His plans for world.
The Israelites were promised they would be special in God's eyes if they did His will by obeying Him:
5 Now therefore, if you will indeed obey my voice, and keep my covenant, then you shall be my own possession from amongst all peoples; for all the earth is mine;
The Psalmist David wants to do God's will and asks for help in doing so:
8 I delight to do your will, my God.
Yes, your law is within my heart.”
10 Teach me to do your will,
for you are my God.
Your Spirit is good.
Lead me in the land of uprightness.
Jesus Christ regards those who do God's will as his family:
35 For whoever does the will of God is my brother, my sister, and mother.”
God listens to the requests of those who do His will:
14 This is the boldness which we have towards him, that if we ask anything according to his will, he listens to us.
Jesus tells us that we must do more than just talking about doing God's will:
21 Not everyone who says to me, ‘Lord, Lord,’ will enter into the Kingdom of Heaven; but he who does the will of my Father who is in heaven.
It may be that God's will may involve problems for us:
17 For it is better, if it is God’s will, that you suffer for doing well than for doing evil.
19 Therefore let them also who suffer according to the will of God in doing good entrust their souls to him, as to a faithful Creator.
The apostle Paul was not always sure what God's will for him was:
10 requesting, if by any means now at last I may be prospered by the will of God to come to you.
32 that I may come to you in joy through the will of God, and together with you, find rest.