Looks thin, like it was in heavy shade before being put where it is now. If it was indoors for some time and then got suddenly exposed to hot summer sun it probably burned.

Thanks so much for your reply, bboy---it was indoors at the nursery, and we brought it outside. That's when it started to turn brown but we never had that problem with other Arecas when we brought them outside from indoors. It's thin because I've been trimming off the brown fronds so it's fairly sparse at the moment.

Do you have any suggestions as to how I should take care of it now? Should I put it in the shade? Thank you so much!