Import XLS file from GCS to BigQuery
Bigquery don't support xls format. The easiest way is to transform the file in CSV and to load it into big query.
However, I don't know your xls format. If it's multisheet you have to work on the file.
I have some .xls datas in my Google Cloud Storage and want to use airflow to store it to GCP. Can I export it directly to BigQuery or can i use additional library (such a pandas and xlrd) to convert the files and store it into BigQuery? 
Thanks