Mapping value error in yaml file

[BruceGrove92]

My secrets-binance file looks like this

cd src
touch secrets-binance.yaml
echo "api_key: ''" >> secrets-binance.yaml
echo "api_secret: ''" >> secrets-binance.yaml

I get a scanner error

mapping values are not allowed here
in "./secrets-binance.yaml", line 3, column 17

does anyone know what i've done wrong, I am not very experienced

Thank you