Ask HN: How do I improve my professional communication skills?

Ironic - you haven't given us any context, you haven't told us what kinds of audiences of colleagues you need to communicate with, what topics you need to talk about. Nothing.

The main point in communication is to determine who you are talking to, what information they need, what they already know, and then determine what you'll say.

Then you work out how to say it, and practise the delivery.

It's non-trivial, requires work, and doesn't come for free.