Im quoting the lines from this book chapter
"Schematic illustration for gene expression of microarray data. Figure modified from . From the computational perspective, the microarray data is described as an N × M matrix. Each row describes a sample and each column represents a gene except the last column which means the class label of each sample. gi, j is a numeric value representing the gene expression level of gene j in the i-th sample. ci is the class label of the i-th sample "
It says the last column is the label what exactly is the label I understand samples in rows and genes in columns , and the last column is the class label what kind of label is it?