This is the 957th most frequent Finnish word.
iisalmessa
"Iisalmessa" means "in Iisalmi," referring to being located in the town of Iisalmi in Finland.
Here, "iisalmessa" is used to indicate the location where the action of visiting took place (in this case, the town of Iisalmi).
Kerran kävin Iisalmessa ystävieni kanssa.
Once, I visited Iisalmi with my friends.
In this example, "iisalmessa" denotes the location related to the described state of inhabitation.
Iisalmessa asuu noin kaksikymmentätuhatta ihmistä.
About twenty thousand people live in Iisalmi.
"iisalmessa" here specifies the place where the events referred to in the sentence occur.