It's not just an understanding the text is clear.
It says there's 144000 Jewish virgins that has come to Jesus Christ and will be evangelists to the World during the time of Jacob's trouble (Israel's trouble) what is also called the Tribulation, but the proper term is Jacob's trouble when the world will be in turmoil and basically most of the world will hate on Israel (we can see the build up to this right now).

Re 7:1 ¶ And after these things I saw four angels standing on the four corners of the earth, holding the four winds of the earth, that the wind should not blow on the earth, nor on the sea, nor on any tree.
Re 7:2 And I saw another angel ascending from the east, having the seal of the living God: and he cried with a loud voice to the four angels, to whom it was given to hurt the earth and the sea,
Re 7:3 Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads.
Re 7:4 And I heard the number of them which were sealed: and there were sealed an hundred and forty and four thousand of all the tribes of the children of Israel.
Re 7:5 Of the tribe of Juda were sealed twelve thousand. Of the tribe of Reuben were sealed twelve thousand. Of the tribe of Gad were sealed twelve thousand.
Re 7:6 Of the tribe of Aser were sealed twelve thousand. Of the tribe of Nepthalim were sealed twelve thousand. Of the tribe of Manasses were sealed twelve thousand.
Re 7:7 Of the tribe of Simeon were sealed twelve thousand. Of the tribe of Levi were sealed twelve thousand. Of the tribe of Issachar were sealed twelve thousand.
Re 7:8 Of the tribe of Zabulon were sealed twelve thousand. Of the tribe of Joseph were sealed twelve thousand. Of the tribe of Benjamin were sealed twelve thousand.

Re 14:1 ¶ And I looked, and, lo, a Lamb stood on the mount Sion, and with him an hundred forty and four thousand, having his Father's name written in their foreheads.
Re 14:2 And I heard a voice from heaven, as the voice of many waters, and as the voice of a great thunder: and I heard the voice of harpers harping with their harps:
Re 14:3 And they sung as it were a new song before the throne, and before the four beasts, and the elders: and no man could learn that song but the hundred and forty and four thousand, which were redeemed from the earth.
Re 14:4 These are they which were not defiled with women; for they are virgins. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men, being the firstfruits unto God and to the Lamb.
Re 14:5 And in their mouth was found no guile: for they are without fault before the throne of God.

they're a very special group of guys.
The main reason people are confused is they use Alexandrian bibles, those that Egyptian gnostics altered.
People should use Antioch Bibles like the King James (The New King James is an Alexandrian one, it's title is a lie, it is not a King James Bible)

Here's a simple explanation of it:
[link to www.letusreason.org]

----------------------

Anyway back to the Rapture since it is what concerns us because that is the next step on the time table.

Some more things to ponder:
[link to raptureready.com]
[link to raptureready.com]
[link to according2prophecy.org]
[link to khouse.org]
[link to khouse.org]
[link to khouse.org]
[link to khouse.org]