The /bin/false is a special shell which returns a nonzero error code for blocking access by a user.
The /etc/nologin is used to block logins for accounts and echo a message.

The /etc/profile is the global configuration file that affects all users' environment if they use the bash shell. The user's ~/.bash_profile, if et exists, is the next script that's sourced. This script calls, or sources, ~/.bashrc.

Multiple Command Operators

The semicolon causes all listed commands to be executed independently.
make modules ; echo DO MAKE MODULES_INSTALL NEXT

The double ampersand causes the second command to be excuted if the first command has an exit status of 0 (success).

The double pipe is opposite of the double ampersand.