I have seen that beore and cannot remember why I got it but you might want to use the complete path starting from your root directory.
Something in Linux
bookings_df <- read.csv("~/projects/Course 7/Week 3/hotel_bookings.csv")
It has been a long time since I used Windows but perhaps
bookings_df <- read.csv("C:/projects/Course 7/Week 3/hotel_bookings.csv")
Otherwise shut down R/Rstudio and start afresh.