what is the biological meaning of chromosome cytoband except centromere? they contain more genes or more active than other regions?
The cytobands/karyotype  bands/chromosome bands/G banding etc are old fashioned data. They date back to before we had genome sequences, when the way we used to identify chromosomes and chromosome regions by staining metaphase chromosomes with Giemsa, then viewing them with a microscope. Heterochromatic (closed chromatin, low gene density) regions stain darker than euchromatic (open chromatin, high gene density) regions. Bioinformatically, they're obsolete as genome coordinates are far more accurate and meaningful, however people still use them as a shorthand for identifying genomic regions; it's much quicker, easier and more memorable to say 14q21.3 than it is to say 14:46695396-50395063. I wouldn't use them for looking at heterochromatin vs euchromatin these days either, I would instead look at actual gene density and publicly available DNase sensitivity for open/closed chromatin.