Some Student visas include a rule that can limit your ability to apply for another visa while you are in Australia. The effect depends on the exact rule on your visa and whether any exception applies.
Some Student visas may include a "no further application" rule. This rule is not intended to be used for every student, because it can affect students who want to continue studying or training after their course.
This type of rule is more likely for some government-supported students, including some Foreign Affairs or Defence students, or students financially supported by an Australian or foreign government.
If the rule applies, it may stop the person from applying for most other visas while in Australia. Some exceptions may still apply, so the exact wording on the visa matters.