Pride (Vanity), is excessive belief in one's abilities, such that you don't give credit to God. Pride is also failure to give others credit due them - if someone's Pride bothers you, then you are also guilty of Pride. Aquinas argued that all other sins stem from Pride, making this one of the most important sins to focus on: "inordinate self-love is the cause of every sin...the root of pride is found to consist in man not being, in some way, subject to God and His rule."
Christian teaching against pride encourages people to be submissive to religious authorities in order to submit to God, thus enhancing church power. There need not be anything necessarily wrong with pride because pride in what one does can often be justified. There is certainly no need to credit any gods for the skills and experience that one has to spend a lifetime developing and perfecting; Christian arguments to the contrary simply serve the purpose of denigrating human life and human abilities.
It's certainly true that people can be overconfident in their own abilities and that this can lead to tragedy, but it's also true that too little confidence can prevent a person from achieving their full potential. If people won't acknowledge that their achievements are their own, they won't recognize that it is up to them to keep persevering and achieving in the future.
Prideful people, those guilty of committing the deadly sin of pride, are said to be punished in hell by be "broken on the wheel." It's not clear what this particular punishment has to do with attacking pride. Perhaps during medieval times being broken on the wheel was an especially humiliating punishment to have to endure. Otherwise, why not be punished by having people laugh at you and mock your abilities for all eternity?
This image appeared in 1496 in Le grant kalendrier des Bergiers, published by Nicolas le Rouge in Troyes, France. We can see here several prideful people being broken on a couple of wheels.
Further Reading: Pride: The Seven Deadly Sins, by Michael Eric Dyson