In a simple case of all of the files having the same column structure and being stored in the current working directory, the code can look like this.
library(openxlsx)
library(dplyr)
FileNames <- list.files(path = ".", pattern = "xlsx$")
FILES <- lapply(FileNames, read.xlsx)
AllDat <- bind_rows(FILES)
The data frame AllDat contains all of the data.