What is the meaning of the 144,000 in Revelation?
The two most common interpretations and understandings of the 144,000 and Revelation are either literal or symbolic. Some people believe that there is a literal 144,000 Jews that God will seal to protect them during the end times and the Great Tribulation.
This generally comes from the ideas of dispensationalism that teach that the Church and the nation of Israel are two separate entities in the end times. They have two different methods God will use for their salvation.
Another approach is the symbolic approach. Because much of Revelation can be viewed as symbolic instead of literal, many people take the numbers that make 144,000 as symbolic to represent the church and Israel.
Because there are 12 tribes of Israel and the 12 apostles of the church, many people take those and multiply them to get 144. The 1000 comes from the idea of myriads upon myriads, an uncountable number. This is a great multitude in heaven and chapters like Revelation 4-5.
The number 1000 in the Bible conveys the idea of great multitudes that may or may not be able to be counted. So people who interpret revelation symbolically say this represents believing Gentiles and believing Jews as the whole church of God in the end times.
These people also believe that the church will suffer during the Great Tribulation along with everyone else. Some present ideas that God will somehow protect the church even though it is in the world during this time period. Much of your interpretation of revelation comes from your doctrinal stances and interpretive method.