I think you are a little bit confused about RStudio, IDE stands for Integrated Development Environment and your questions is not about the IDE, is about how to import data from excel and categorize a continuous variable using the R programming language.
Also, the best way for asking a question here, is with a minimal REPRoducible EXample (reprex), since it seems like you are new to R, I'm going to try to make one for you this time.
I think this is similar to what you want to do, so we can start from here
library(openxlsx)
library(dplyr)
# You could read your file with something like this
# df <- read.xlsx("path/to/your_file.xlsx", sheet = 1)
# Made up data to simulate yours since I don't have access to your actual file
df <- data.frame(data_ver = 1:100)
df %>%
mutate(slots = cut(data_ver,
breaks = c(1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100),
labels = letters[1:10]))
#> data_ver slots
#> 1 1 <NA>
#> 2 2 a
#> 3 3 a
#> 4 4 a
#> 5 5 a
#> 6 6 a
#> 7 7 a
#> 8 8 a
#> 9 9 a
#> 10 10 a
#> 11 11 b
#> 12 12 b
#> 13 13 b
#> 14 14 b
#> 15 15 b
#> 16 16 b
#> 17 17 b
#> 18 18 b
#> 19 19 b
#> 20 20 b
#> 21 21 c
#> 22 22 c
#> 23 23 c
#> 24 24 c
#> 25 25 c
#> 26 26 c
#> 27 27 c
#> 28 28 c
#> 29 29 c
#> 30 30 c
#> 31 31 d
#> 32 32 d
#> 33 33 d
#> 34 34 d
#> 35 35 d
#> 36 36 d
#> 37 37 d
#> 38 38 d
#> 39 39 d
#> 40 40 d
#> 41 41 e
#> 42 42 e
#> 43 43 e
#> 44 44 e
#> 45 45 e
#> 46 46 e
#> 47 47 e
#> 48 48 e
#> 49 49 e
#> 50 50 e
#> 51 51 f
#> 52 52 f
#> 53 53 f
#> 54 54 f
#> 55 55 f
#> 56 56 f
#> 57 57 f
#> 58 58 f
#> 59 59 f
#> 60 60 f
#> 61 61 g
#> 62 62 g
#> 63 63 g
#> 64 64 g
#> 65 65 g
#> 66 66 g
#> 67 67 g
#> 68 68 g
#> 69 69 g
#> 70 70 g
#> 71 71 h
#> 72 72 h
#> 73 73 h
#> 74 74 h
#> 75 75 h
#> 76 76 h
#> 77 77 h
#> 78 78 h
#> 79 79 h
#> 80 80 h
#> 81 81 i
#> 82 82 i
#> 83 83 i
#> 84 84 i
#> 85 85 i
#> 86 86 i
#> 87 87 i
#> 88 88 i
#> 89 89 i
#> 90 90 i
#> 91 91 j
#> 92 92 j
#> 93 93 j
#> 94 94 j
#> 95 95 j
#> 96 96 j
#> 97 97 j
#> 98 98 j
#> 99 99 j
#> 100 100 j