Hi @Punta1980,
A warm welcome to the Bunnings Workshop community and thank you for your question.
The longer light green grass looks like it is Couch, which is another variety of grass that grows differently from Buffalo, which makes up most of your lawn.
Unfortunately, I'm not aware of a product you could use to remove it. If you wanted to get rid of it, you'd have to remove all the grass and start again.
Having different species of grass in your lawn is pretty common. I wouldn't worry about it too much, just keep it mown and you won't realise it is there.
Let me know if you have any further questions.
Jacob
