arch - architecture stuffs like riscv initialization and linker config
boards - boards definition files, stuffs specific to a single pcb
cmake - cmake scripts
doc - documentation
drivers - device drivers, including SoC devices (timers, SPI, etc) and external device drivers.
dts - common DTS files (SoC level, arch level) and bindings between dts names and driver names.
include - repetition of the folder structure but for all hte headers that could fit in it, also DTS bindings headers.
kernel - kernel
lib - lib
misc - nothing
modules - external modules build, config, and additional files for external elements required to build zephyr (modules folder in workspace correspondant)
samples - samples
scripts - build generation scripts, west build, debug, etc scripts, runners, debuggers.
share - share
snippets - snippets
soc - soc level files, sorted by arch then by vendor then by platform.
submanifests - submanifests
subsys - zephyr subsystems
tests - tests to test specific features of zephyr, buildable like samples.
west.yml - module definition file