Some coding bootcamps will nudge you to start a blog. At least the one I attended did.
I started a technical blog on programming back when I was a student at Hack Reactor and it taught me several key lessons:
Technical topics are best understood when you work through teaching it to others.
Writing about something makes you realize just how unclear specific constructs are in your head.
You turn your vague mental models into presentable, crystal clear explanations of how something works.
The thing about "teaching" that nobody talks about is that teaching solidifies the teacher's understanding more than the student's understanding.
That's because there are two kinds of teaching:
Convey a message and transmitting an idea from one brain to another.
You are showing the ropes for someone else to actually climb and develop themselves.
The former kind of teaching benefits the teacher because the teacher is the one with the most difficult assignment of presenting a coherent message. The latter kind of teaching benefits the student because the student must climb the ropes themselves.
As an effective learner, you want to be the teacher that conveys coherent messages to others, and you want to be the student that is actively showing up, doing the work, and participating in the process of developing your own skills.
This is why "starting a blog" about the technical topics you learn in a coding bootcamp is great advice.