Its easy to make histograms with hist() to show you the distribution of a set of data.
For actual bar plot, such as you would make in excel, there's also a function called barplot(). I think you have more control, however, you you use the regular function plot() with a few modifications.
I work with a population of plants that often go dormant. I had a proportion table like the output below for 8 years of data. Some plants were around all 8 years, but many went dormant for 1 or more years.
I made the proportion table using table() and prop.table(); round() gets rid of the excess decimal places.
> round(prop.table(table(factor(S_tot_yrs_pres_03_10))),3)
The table output is like this:
0 1 2 3 4 5 6 7 8
0.009 0.120 0.098 0.079 0.110 0.144 0.180 0.140 0.120
This give me the portion of plants that grew a certain number of years. I grabbed this data and the plotted it as a bar graph ("column" graph in Excel parlance) using plot() with a few extra calls.
The code was this:
plot(years_above_ground, portion_of_pop, type="h", lwd=50, lend=2, col=2, ylim=c(0,.25), xlab="years of growth", ylab="portion of pop")
The key to making this look like a bar graph are these three pieces
type="h", #This tell it to make a graph of type "histogram"
lwd=50, #This tell the line width to be 50; otherwise it will plot skinny lines.
lend=2, #this makes the line end style to be flat; the default is rounded.
