This is a well-known Jesus saying. It has to do with the potential that wealth has for corrupting and the difficulty of attaining oneness with God when someone places too much value on earthly possessions.
It is also fascinating example of Biblical mistranslation. If you look at the original Aramaic, the word for camel is "gamlo". When the word gamlo was translated into Greek, it was translated literally. However, the translator may not have considered that the word also had a double meaning in Aramaic. Gamlo also meant "A thick rope made of camel hair used to bind ships". Over time, gamlo came to mean either camel or rope.
Given that Jesus was speaking to fishermen, it more likely that he used the second meaning of gamlo, rather than the first. So the original saying is probably closes to... "It is easier to thread a rope through the eye of a needle than for a rich man to enter the kingdom of God"... "
In this case, the mistranslation does not affect the message Jesus was trying to convey. The idea is that it impossible for someone who is attached to earthly wealth to obtain heaven. You cannot have true spiritual wealth and love money. You cannot worship two masters.
Unfortunately, the mistranslation has influenced the interpretation by some individuals who are uncomfortable with Jesus' views about earthly wealth. To justify their "hope" that it is possible for a wealthy person to enter the kingdom of God, some have taken Matthew 19:24 to mean that heaven's gate are very narrow and thus you have to walk a "straight path" to enter... straight path being a metaphor for living a good life and observing all the laws.
The idea of walking of straight path is much easier to visualize with the camel than with the rope.