Situational application means using different behaviors depending on the situation you are in.
Think about how you act differently when you are at home compared to when you are at school or in a restaurant.
At home, you might feel more comfortable and relaxed, so you might talk louder or wear your pajamas all day. But when you are in public, you might need to be more polite and quiet, and wear nice clothes.
Situational application is about adapting your behavior to fit the situation you are in, so that you can be successful and get what you need. It's like being a chameleon and changing colors to blend in with your surroundings.
It's important to be aware of different situations and what kind of behavior is appropriate. That way, you can learn to adjust your behavior to fit in and get the result you want.