Slaaf is the Dutch word for slave.
On 1 July 1863, slavery was abolished in the Dutch colonies of Suriname and the Netherlands Antilles. In practice, the enslaved people were bound to work for their former enslavers for another ten years, to ease the transition. The owners received compensation for the loss of their chattel.
The National Archives of the Netherlands has several indexed sources regarding enslaved people, including manumission records.

Enslaved people working at a Suriname plantation, 1850. Credits: Th. Bray, Wikimedia Commons (public domain)