The number 4 derives its meaning from creation. On the fourth day of what is called 'creation week' God completed the material universe. On this day he brought into existence our sun, the moon, and all the stars (Genesis 1:14 - 19). Their purpose was not only to give off light, but also to divide the day from the night on earth, thus becoming a basic demarcation of time. They were also made to be a type of signal that would mark off the days, years and seasons.
Interestingly, the Hebrew word for 'seasons' in Genesis 1:14 is moed (Strong's Concordance #H4150), which literally translated is "appointed times" (divine appointments) in reference to God's festivals. This is the earliest known allusion to what would later be called the Holy (or Feast) days (periods) of worship, which are seven in number.
The 4th of the Ten Commandments is to remember and keep God's holy Sabbath day (Exodus 20:9 - 11). The Sabbath day is tied directly to the creation week. God himself made the period between Friday sunset and Saturday sunset extra special when he rested on it after bringing everything into existence the previous six days (Genesis 2:1 - 3, Exodus 20:11).
Appearances of the number four
One of the top ten most frequently mentioned women in the Bible, Eve, is only referenced four times (Genesis 3:20, 4:1, 2Corinthians 11:3 and 1Timothy 2:13).
Psalm 107 is the only section or chapter in God's word that contains the exact same phrase four times (Psalm 107:8, 15, 21 and 31).
The apostle Paul was a man familiar with 4 major first century cultures. He was a Roman citizen, he was a Jew who spoke Greek as well as Hebrew, and he was a Christian.
The Garden of Eden had a river which parted into the headwaters of four other rivers. These rivers were the Pison, Gihon, Hiddekel and the Euphrates (Genesis 2:10 - 14).
After Jesus was nailed and hung on a cross, Roman soldiers divided up his clothes into four parts (one for each soldier - John 19:23).
The four witnesses of God on earth are miracles, wonders, signs and the gifts of the Holy Spirit (Hebrews 2:4).
The number of times rainbows are referenced in scripture are four (Genesis 9, Ezekiel 1:28, Revelation 4:3, 10:1).
Ezekiel, prophecy and the number 4
In Ezekiel's well-known 'wheel in the middle of a wheel' vision (Ezekiel 1, 10) he sees four living creatures transporting a throne with four sides and four wheels. Each of the living creatures (likely Cherubim, a class of angels) has four faces (the face of a man, lion, ox and eagle) and four wings (1:6).
Later in the book that bears his name, Ezekiel is told to proclaim to Israel that an end is coming upon 'the four corners of the land' (Ezekiel 7:2). In chapter 14 the prophet is told by the Eternal to ask Israel's unrepentant elders to repent or else four sore judgments will come upon Jerusalem. They are the sword, famine, wild beasts or animals, and pestilence (14:21).
Additional info on the Biblical Meaning of 4
There are 4 gospel accounts of Jesus' life and ministry. Each of these emphasizes a unique aspect of his sacrifice and ministry. Matthew's focus is on Christ being the son of David and a King. Mark highlights the suffering servant aspect of his ministry. John proclaims Jesus is the One and Only begotten Son of God. And Luke showcases him as the Perfect Man.