How to get the cell's label of 10x data_file with scanpy?

I just wanna to get the cell’s labels (annotations) after loading the data by scanpy, but I do not know how to do it and it is puzzled that where is the label in the data??
Following the tutorial, I just read pbmc 3K data by doing follow:

adata = sc.read_10x_mtx(‘filtered_gene_bc_matrices/hg19/’, var_names = ‘gene_symbols’, cache=True)

and where is the cell label in the adata??
Can someone help me??
Many THX :slight_smile: