how to place SL in python code

You need to select the order type as SL and send the trigger price. The trigger price has to be sent as (last price - 50) in your case.

You can enter the last price as trigger price, that is not an issue.

you mean something like this is correct , can any python developer help me . im new in python.
order_id = kite.place_order(tradingsymbol="BANKNIFTY20OCTFUT",
exchange=kite.EXCHANGE_NFO,
transaction_type=kite.TRANSACTION_TYPE_BUY,
quantity=tradeQuantity,
order_type=kite.ORDER_TYPE_SL,
product=kite.PRODUCT_MIS,
trigger_price= kite.ltp()-50,
variety = kite.VARIETY_REGULAR)

ohh you mean need to write seperate code for SL , is there any way to do it in single code?

stoploss_price = kite.ltp('NSE:TATASTEEL')['NSE:TATASTEEL']['last_price'] - 50

kite.place_order(tradingsymbol="TATASTEEL",
exchange=kite.EXCHANGE_NSE,
transaction_type=kite.TRANSACTION_TYPE_SELL,
quantity=1,
trigger_price=stoploss_price,
price=stoploss_price,
order_type=kite.ORDER_TYPE_SL,
product=kite.PRODUCT_MIS,
variety = kite.VARIETY_REGULAR
)

this works for me but creates 3 SL orders why ?

yes but i think when i used SM it works fine