It counted slaves as 3/5 of a person. They didn't know whether to count slaves as part of the population or as property. The result ended up being the three-fifths compromise.
Slavery was a hotly debated topic at the Constitutional Convention. On one hand, Southern states wanted slaves to count towards population. This would increase the amount of representatives the Southern states had in the House of Representatives.
On the other hand, the South did not want slaves to count towards the population because this would result in the Southern states paying more direct taxes to the federal government.
The North felt the opposite than the South. Nonetheless, this issue was solved by the 3/5ths Compromise. This compromise stated that every 5 slaves would count as 3 people towards a states population for both representation and taxation.
