Comparison operators last line of code

n_apps_less_9 = len(apps_data[1:]) - len(ratings)
why are we using app_data[1:], doesnt that include the entire table after the first column ?
could someone explain the meaning of this code to me ?

As the first row of the data is header. it contains all the headings like ‘Genres’, ‘Apps’ etc.

While comparing we don’t need to count length of it. We just want all the rows that contains values.

So when we use app_data[1:] it starts from index value 1 which contains all the data and doesn’t consider header row.

header value= app_data[0]: [‘App’, ‘Category’, ‘Rating’, ‘Reviews’, ‘Size’, ‘Installs’, ‘Type’, ‘Price’, ‘Content Rating’, ‘Genres’, ‘Last Updated’, ‘Current Ver’, ‘Android Ver’]

rest data= app_data[1:]: [‘Photo Editor & Candy Camera & Grid & ScrapBook’, ‘ART_AND_DESIGN’, ‘4.1’, ‘159’, ‘19M’, ‘10,000+’, ‘Free’, ‘0’, ‘Everyone’, ‘Art & Design’, ‘January 7, 2018’, ‘1.0.0’, ‘4.0.3 and up’]
[‘Coloring book moana’, ‘ART_AND_DESIGN’, ‘3.9’, ‘967’, ‘14M’, ‘500,000+’, ‘Free’, ‘0’, ‘Everyone’, ‘Art & Design;Pretend Play’, ‘January 15, 2018’, ‘2.0.0’, ‘4.0.3 and up’] …