It looks like the words "buy" and "sell" are mixed up in the help code you provided then.

I made the changes in red:

optional arguments:
  -h, --help            show this help message and exit
  --from SOURCE         the source address
  --get-quantity GET_QUANTITY
                        the quantity of GET_ASSET that you would like to
                        receive
  --get-asset GET_ASSET
                        the asset that you would like to sell buy
  --give-quantity GIVE_QUANTITY
                        the quantity of GIVE_ASSET that you are willing to
                        give
  --give-asset GIVE_ASSET
                        the asset that you would like to buy sell
  --expiration EXPIRATION
                        the number of blocks for which the order should be
                        valid
  --fee_required FEE_REQUIRED
                        the miners' fee required to be paid by orders for them
                        to match this one; in BTC; required iff buying BTC
                        (may be zero, though)
  --fee_provided FEE_PROVIDED
                        the miners' fee provided; in BTC; required iff selling
                        BTC (should not be lower than is required for
                        acceptance in a block)
$