How can I make 4 columns into one?

I am not sure what you want but this may do. I am calling your data set dd

pivot_longer(dd, cols = c( "variable1", "variable2", "variable2", variable4), values_to = "Results", names_to = "Names")

A screenshot is really not very usefull. See FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A handy way to supply some sample data is the dput() function. In the case of a large dataset something like dput(head(mydata, 100)) should supply the data we need. Just do dput(mydata) where mydata is your data. Copy the output and paste it here.