Let's not talk yet. I'm busy. It's very hot. What do you mean, drink plenty of water without heatstroke?

This sentence means that this person has no time to chat now, and cares about the other person's heatstroke.

"Don't talk yet, I'm busy, it's hot, drink more water, don't get heatstroke" means that the speaker is busy now and has no time to chat with the other person, but he still cares about the other person when he is busy, reminding him that the weather is very hot and needs to drink more hot water to avoid heatstroke.