What does the number seven mean in biblical terms?
Most of the time in the Bible, seven stands for the number seven. That is, most of the time it has no more significance than as a count of something.
Sometimes, however, there appears to be a special meaning to certain numbers, including seven. Three is often interpreted as being spiritually complete (the so-called Trinity, three Patriarchs—Abraham, Isaac, and Jacob, etc). Four represents physical completion (four sides of a square room, four corners, four directions). Using this reasoning, combinations of three and four represent total completion. This would include twelve—three times four—(tribes of Israel, apostles) and seven—three plus four—(days of week).
Some examples of seven used figuratively are:
Psalm 12:6—“ The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times.”
Proverbs 9:1—“Wisdom hath builded her house, she hath hewn out her seven pillars.”
Revelation 1:4—“To the seven churches which are in Asia.” (There were more than seven, but by singling out these seven, he indicates all of the others as well.)
Revelation 13:1—“ And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.” (The obvious symbolism here is not completeness, but that the beast is the Roman government, since Rome was known as the city built on seven hills.)
That last example shows the difficulty of taking numbers symbolically. Sometimes the symbol may be completeness. Sometimes the symbol may relate to something related directly to the number. Most of the time the number means a number.