Python: Error when trying to calculate correlation of data

Following the tutorial, I try to calculate the correlation of the data but it gives me an error I can’t seem to fix. Is there anyone who can help with this? Thanks in advance.

sales = pd.read_csv(
    'data/sales_data.csv',
    parse_dates=['Date'])

corr = sales.corr()

corr

ValueError: could not convert string to float: ‘2013-11-26’
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