What are communication skills?

Communication skills are primarily about making sure the recipient gets the exact message you are trying to convey. If that message can be conveyed in a crisp manner, that is an added bonus.

There is also an emotional aspect to communication, which is to create the intended emotional state in the recipient.

Here I have made just a brief, for more you can click the given link: English Communication & Soft Skills

Great question. Just want to add on:

Communication also includes listening and grasping. It is not just language proficiency in talking or writing. In fact at times it is ok to goof up grammar a bit but still make sure your point went correct across the table.

So in short, make sure to understand logically what information is needed, what the receiver is capable of understanding and at what maturity the receiver is at, and then lastly organize your thoughts to deliver.

PS: It’s a skill, not an art. Which means it’s not in your genes or some non sense, but comes with sheer practice.
So make sure to learn it with equal importance as your python or tech skills.