We can map all of $\mathbb{P}^1$ to a single point: $$p \colon \mathbb{P}^1 \to \mathbb{P}^1$$ and this map clearly has $p^2 = p$. Thus, in the category $\mathsf{Mot}$ we have $$h(\mathbb{P}^1) = h(1) \oplus \mathbb{L}$$ where $1$ corresponds to the point and $\mathbb{L}$ is some motive called the Lefschetz motive.