...
module avail
module help <package>/<version>
module load <package>/<version>
module unload <package>/<version>Loading a module adds prepends the path to the binaries of a software package to environment variable PATH. This makes executables of software packages visible. For example, if you want to work with gcc, version 9,, load the appropriate module and the binary becomes visible for your shell.
module load gcc/9.3.0
gcc --version
Loading a module manipulates the shell environment to make software visible for shell commands. Note, these changes of environmental variables are fully reversible and are taken back, if a module is unloaded.
...