Nǐ hǎo means hello – the first Chinese word of the training.
You are standing in front of a low house with somebody calling “hello” inside it: low (niedrig in German) and house (Haus in German) give you nǐ hǎo. In front of the house stand two trampolines, one for each syllable. They tell you that both syllables go down and then back up again.
That pitch movement is what is new about Chinese. Where it is part of the image, you cannot confuse it later.