When we speak, our voice can change in different ways depending on what we're trying to say. This is called "inflection".
Think of it like this: imagine you have a toy car, and you can make it go fast or slow. Inflection is like the different speeds you can make the toy car go. Just like you can control the car, you can control your voice to make it sound different depending on your mood or what you're trying to convey when you speak.
For example, you might speak louder and faster when you're excited, or you might speak softly and slowly when you're feeling sad. You might emphasize certain words in a sentence to show that they're more important than others.
Inflection can also change the meaning of what we say. For instance, if we say "I didn't take the last cookie", the meaning changes completely depending on where we put the emphasis: "I didn't take the last COOKIE" versus "I didn't take the last cookie".
In short, inflection is like a tool we use when we talk to express ourselves, emphasize what we mean and make ourselves understood. It's like playing with your voice to make your words have more meaning and impact.