Importing time series data into R

Hi R users
I am currently learning R and I am usimng it for time series analysis. My Issue is I have imported the campylobacter data into R. When I am attaching the dataset using

attach(campylobacter_germany_xlsx) I get the error
The following objects are masked from campylobacter_germany_xlsx (pos = 3):

case, date

How do i go about overcoming this

Thank you fr your help