What does commutes in $hTop_*$ mean and how does the proof following this sentence show it?
The proof says this follows from $q_1m \simeq 1_x \simeq q_2m$ where $q_1, q_2 : X \lor X \rightarrow X$ are defined as projections that send $x$ to $(x,x_0)$ or $(x_0,x)$, respectively and $X \lor X$ is viewed as the subspace of $X \times \{x_0\} \cup \{x_0\} \times X$.

It means that the functions $\Delta$ and $k \circ m$ are (base-point preserving) homotopic.