You need to reshape your data so the TF label is in one column and the values are in another. It seems as if the SN250 column is not needed, so I dropped it in the example below. I invented a small data set for this example
library(tidyr)
library(ggplot2)
library(dplyr)
DF <- data.frame(SN250 = 1:3, TF1 = rnorm(3), TF2 = rnorm(3), TF3 = rnorm(3))
DF
#> SN250 TF1 TF2 TF3
#> 1 1 0.1809112 -0.8879696 0.45406388
#> 2 2 0.4423818 0.9321035 0.31701018
#> 3 3 1.1232862 0.7158731 -0.07038791
DFplot <- DF %>% select(-SN250) %>% #drop the first column
pivot_longer(cols = TF1:TF3, names_to = "TF", values_to = "Value")
DFplot
#> # A tibble: 9 x 2
#> TF Value
#> <chr> <dbl>
#> 1 TF1 0.181
#> 2 TF2 -0.888
#> 3 TF3 0.454
#> 4 TF1 0.442
#> 5 TF2 0.932
#> 6 TF3 0.317
#> 7 TF1 1.12
#> 8 TF2 0.716
#> 9 TF3 -0.0704
ggplot(DFplot, aes(TF, Value)) + geom_boxplot()

Created on 2020-06-03 by the reprex package (v0.3.0)