Units of specific CRS projection?

Question

I use a shapefile with CRS ("+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0"). I want to calculate a buffer around the points with 'extract' from raster package. How can I know the units in this layer? Is it in meters? My idea is to calculate 1X1 km , thus buffer=1000. Is that correct?

try1 <- extract(raster, 
                points,
                fun=mean, na.rm=T,
                sp = TRUE, # create spatial object
                buffer = 1000,
                method='simple',
                weights=T, 
                normalizeWeights=F)

Answer 1

+proj=longlat is in angular units, degrees by default.

Better if you can project your dataset before, to a conformal projection (to preserve the circular buffer shape) appropriate for your work area (so that the distance deforms as little as possible).