You cannot "convert" a visitor visa to a work permit.
If your friend wants to apply for a work permit, the first step is to obtain a job offer from an employer in Canada. That employer must then obtain an approved LMIA, including advertising the job to prove no Canadian could be hired for the role. If the LMIA is approved, your friend then applies for a closed work permit which is tied to that specific employer.
Depending on the job offer/NOC, you may need ECA for education and IELTS for language. You cannot work until you have approved LMIA and closed work permit which can take many months.
You cannot "convert" a visitor visa to a work permit.
If your friend wants to apply for a work permit, the first step is to obtain a job offer from an employer in Canada. That employer must then obtain an approved LMIA, including advertising the job to prove no Canadian could be hired for the role. If the LMIA is approved, your friend then applies for a closed work permit which is tied to that specific employer.