Thousands of people pray simultaneously and God hears them all at the same time. He knows everything that is happening right now on earth. He also knows our every thought, action, and words, including our prayers. God knows all things (1 John 3:20). Every affairs of man are not hidden to God's eyes (Hebrews 4:13). God knows and hears when all humans are praying.
God understands all languages because He is the Almighty God (Genesis 17:1). He is the God of all mankind and there is nothing too hard for Him to accomplish (Genesis 18:14, Jeremiah 32:17,27). God is able to handle all request made known to Him by us in prayers. He is Omnipotent.
Is every prayer acceptable to God?
The prayer of a man who refuse to hear the Word of God and keep His commandment is an abomination in the sight of God (Proverbs 28:9). This means that a man who refuse to do what's right, and enjoys the vain pleasure of sin should not expect his prayer to be heard by God. In plain words, God refuse to hear the prayer of a disobedient person.
On the other hand, God has His eyes over the righteous and keeps His ears open to their prayers. So it is clear that God only hears the prayer of the righteous.
Who is a righteous person?
A righteous person is one who keeps God's commandments at all times (1 John 3:7, Psalm 119:172).
One last consideration.
There are some prayers of the righteous that God can refuse to hear. Take a quick look at 1 John 5:14, God hears the righteous as long as they ask anything according to His will.
So how can we pray according to God's will?
God's will can be found in the Bible. There is no better place to learn about the will of God outside the Bible. When we pray with God's Word, we remind Him of the things He has promised us, and we make Him act on it.
Remember, the Word of God is alive and active, sharper than any double-edged sword. It penetrates even to diving soul and spirit, joints and marrow (Hebrews 4:12)
So if we pray with Scripture verses (the Word of God), we make our prayers alive and active, sharp and penetrative.
Just imagine.