If you've cut an avocado in two, save it from turning brown by putting a few drops of lemon juice on the pulp or by brushing the avocado half with a little bit of edible oil.
Adding a little lemon juice enhances the flavor of the rice. (The rice tastes good but now it will taste great.) The verb " improve" means to make (something) better or to become better.
Yeah, you just take raw kale and rinse it, and then you add lemon juice and olive oil and salt and pepper and just, you know, massage it until it tenderizes into a nice salad.